This is a homemade take on the Jack in the Box Sourdough Jack — a beef and bacon burger built on toasted sourdough instead of a bun. The honest reason to make it: thick-cut artisan sourdough handles a juicy 80/20 patty better than any standard bun, and the garlic mayo ties everything together in a way the original never quite managed.
The technique that matters
Two things decide whether this burger is great or just okay. First, the sear. An 80/20 patty needs high, dry heat — a cast-iron skillet or a very hot griddle — to build a proper crust before the inside overcooks. Get the pan smoking before the beef touches it, and don’t move the patty for at least two minutes. Second, the final press. After you’ve assembled the burger, set it back on the pan for 30–45 seconds per side. This step melts the cheese fully into the patty, softens the bacon just enough so it doesn’t slide out, and crisps the mayo-coated sourdough one more time. Skip it and you have a good burger. Do it and you have a great one. Use a thermometer — ground beef is done at 160°F (71°C) internal temperature, no guessing.
Ingredient notes
- Sourdough bread: Buy a whole loaf and slice it yourself to about ¾-inch thick. Pre-sliced sourdough from the sandwich bread aisle is too thin and will go soggy under the patty weight.
- Swiss cheese: Deli-sliced Swiss melts more evenly than the pre-packaged shreds. If Swiss is hard to find, Gruyère works and adds a slightly nuttier flavor.
- Thick-cut bacon: Standard thin bacon cooks down to almost nothing here. Go thick-cut — it holds its texture after the final press.
- Garlic for the mayo: Fresh minced garlic is sharper and brighter than garlic powder. If you want a milder flavor, grate the clove on a microplane instead of mincing.
Storage and reheating
Store any cooked patties separately from the bread — assembled burgers go soggy fast. Patties keep in an airtight container in the fridge for up to 3 days. Reheat them in a covered skillet over medium-low heat for 3–4 minutes, adding a splash of water and a lid to keep them from drying out; this also re-melts the cheese. Cooked bacon keeps refrigerated for up to 4 days and crisps back up in a dry pan in under a minute. Sourdough slices can be stored at room temperature for 2 days or frozen for up to a month — toast straight from frozen. Fully assembled burgers are not worth freezing.
What can go wrong
- Patty puffs up in the center: The beef is contracting from heat. Press a shallow dimple in the center of each patty before it goes in the pan — about ¼ inch deep. It flattens out as it cooks.
- Sourdough burns before the patty is done: The bread toasts fast, especially with butter. Toast the bread separately first, then cook the patty. Don’t try to do both at the same time in the same pan.
- Garlic mayo tastes raw and sharp: Raw minced garlic is strong. Let the finished mayo sit for at least 10 minutes before using it — the lemon juice mellows the bite noticeably.
- Cheese slides off instead of melting in: Add both cheese slices in the last 60 seconds of the patty cook, cover the pan with a lid or a bowl, and let the trapped steam do the work. Cheese laid on too early just sweats; too late and it never bonds to the meat.
- Bacon goes limp in the finished burger: Lay the bacon on top of the cheese during the final press step, not underneath it. The direct pan contact keeps it crisper longer.
Gourmet Sourdough Jack-Inspired Burger
Ingredients
For the Burger:
- 1 ½ pounds ground beef (80/20 blend) for juicy, flavorful patties
- 1 teaspoon kosher salt adjust to taste
- ½ teaspoon black pepper freshly cracked
- 4 large sourdough sandwich slices buttered with unsalted butter on one side
- 4 slices Swiss cheese
- 4 slices American cheese
- 8 strips thick-cut bacon cooked until crispy
For the Garlic Mayo Spread:
- ½ cup mayonnaise preferably full fat
- 1 clove garlic minced or finely grated
- 1 teaspoon lemon juice freshly squeezed
- ¼ teaspoon salt to taste
Instructions
- Make the Garlic Mayo: In a small bowl, combine mayonnaise, minced garlic, lemon juice, and salt. Mix well and refrigerate until needed. The flavor intensifies as it rests.
- Form the Beef Patties: Divide the ground beef into 4 equal portions (approximately 6 oz each). Gently shape into patties slightly larger than your bread slices, as they will shrink when cooked. Season both sides with kosher salt and black pepper.
- Cook the Bacon: In a skillet over medium heat, cook the bacon until deeply golden and crispy, about 5–7 minutes. Drain on paper towels and reserve.
- Sear the Patties: Heat a cast iron or heavy-bottomed skillet over medium-high heat (about 375°F / 190°C). Cook the beef patties 3–4 minutes on each side for medium doneness, until a rich brown crust forms. Melt a slice of Swiss and American cheese on each patty in the last minute of cooking. Set aside to rest.
- Toast the Sourdough: On a skillet or griddle, toast the buttered sides of the sourdough slices over medium heat until golden and crisp, about 2 minutes per side. Watch closely to avoid burning.
- Assemble the Burgers: Spread garlic mayo generously on the untoasted side of each sourdough slice. Layer one cheese-covered patty, two strips of bacon, and top with the second slice, mayo side down (untoasted side facing in).
- Final Toast (optional): For an extra crispy finish, toast the assembled burger for 1 more minute per side on a heated griddle or pan, pressing down gently to melt everything together.
Notes
Chef’s Tips:
- Add sautéed onions or a tomato slice for extra moisture and umami.
- For a spicier version, mix a spoon of sriracha into the garlic mayo.
- Swap beef for a plant-based patty to adapt for vegetarians.
Nutrition
Your questions, answered
Can I use a different cut of ground beef instead of 80/20 chuck?
You can, but leaner blends like 90/10 will give you a drier, tighter patty. The fat in 80/20 is what keeps the burger juicy through a full sear to 160°F — going leaner means you need to be more precise with your cook time or you’ll end up with something closer to a hockey puck.
What if I can’t find a good artisan sourdough loaf?
A sturdy Italian or country white loaf works as a backup — you need something with a tight crumb that won’t collapse. Avoid soft sandwich bread entirely; it absorbs the mayo and beef juices and falls apart before you finish eating.
Do I need a cast-iron skillet, or will a regular nonstick pan work?
A nonstick pan will cook the patty through, but it won’t give you the same crust. Cast iron holds heat better and creates the Maillard browning that makes the outside of the patty taste like more than just cooked beef. If cast iron isn’t an option, a stainless steel pan is a closer substitute than nonstick.
Can I make the patties ahead of time?
Yes — shape them, place parchment between each one, and refrigerate for up to 24 hours. Cold patties actually hold their shape better in the pan. Don’t season them until right before they hit the heat, though; salt draws out moisture and can make the surface wet if left too long.
Is there a way to make this without bacon for someone who doesn’t eat pork?
Turkey bacon is the most straightforward swap and cooks the same way. Beef bacon is another option with a smokier, meatier flavor. Either way, cook it until it’s genuinely crispy — both alternatives release more moisture than pork bacon and need the extra time in the pan.
How do I keep the whole burger from falling apart when I eat it?
The final press step is the main thing — it fuses the layers together. Beyond that, spread the garlic mayo all the way to the edges of the bread so the first bite isn’t dry, and let the assembled burger rest for 60 seconds off the heat before you cut or pick it up. That brief rest lets the cheese firm up slightly and everything holds better.