Salsa Blanca is Uruguay’s everyday white sauce — butter, flour, milk, and a little seasoning cooked into something smooth and thick. It takes 30 minutes, uses ingredients you already have, and makes a genuinely useful base sauce that works across a whole week of meals. Make a batch on Sunday and you’ll reach for it constantly.
Ingredient notes
- Whole milk: Use whole milk. Lower-fat milk produces a thinner sauce that doesn’t hold up as well when stored and reheated.
- White pepper: Swapping in black pepper works fine taste-wise, but you’ll see dark flecks in the sauce. Not a problem if it’s going into a lasagna; matters more if you’re spooning it over something pale.
- Nutmeg: Optional but worth using. A small pinch pulls the flavor together. Pre-ground nutmeg is fine here — you don’t need to grate fresh for a pinch.
- Unsalted butter: Salted butter will work, just hold back on the added salt until you taste at the end.
Before you start
The one thing that actually matters is warming the milk before it goes in. Cold milk hitting a hot roux is the main reason sauces turn lumpy — the temperature difference causes the starch to seize unevenly. Warm it in the microwave for 60–90 seconds or in a small saucepan until it’s just steaming, not boiling. The second thing worth knowing: cook the roux for the full two minutes before adding any liquid. Undercooked roux leaves a raw flour taste that doesn’t cook out later, and no amount of seasoning covers it.
What can go wrong
- Sauce seizes into lumps: Usually from adding milk too fast. If it happens, take the pan off the heat and whisk hard. For stubborn lumps, strain the sauce through a fine mesh sieve and return it to the pan.
- Sauce stays thin after 10 minutes: Your heat is probably too low. Turn it up to medium and keep whisking. The sauce needs to reach a gentle simmer to activate the starch in the roux.
- Skin forms on top while cooling: Press a piece of plastic wrap directly onto the surface of the sauce before it cools. This is especially important if you’re making a batch to store — a thick skin on stored sauce is hard to whisk back in.
- Sauce too thick after refrigerating: It will always thicken in the fridge. Add a splash of milk and whisk over low heat to loosen it back to the right consistency.
- Greasy or broken sauce: This happens if the heat is too high for too long. Keep it at medium-low once the milk is in, and don’t walk away.
Keeping and reheating
Salsa Blanca keeps well in the fridge for up to 4 days in an airtight container — press plastic wrap directly onto the surface before sealing to prevent a skin. It also freezes cleanly for up to 2 months; portion it into 1-cup freezer bags or an ice cube tray so you can thaw exactly what you need. To reheat, put it in a small saucepan over low heat with a splash of milk and whisk steadily until smooth. Skip the microwave if you can — it heats unevenly and tends to split the sauce. Skip the cream substitution if you’re planning to freeze a batch; cream-based sauces are more likely to separate on thawing.
Uruguayan Salsa Blanca
Ingredients
- 2 tablespoons unsalted butter Preferably organic for a richer taste.
- 2 tablespoons all-purpose flour
- 2 cups whole milk Warm to prevent lumps.
- ½ teaspoon salt Adjust to taste.
- ½ teaspoon white pepper Freshly ground for best flavor.
- 1 pinch nutmeg Freshly grated, optional.
Instructions
- In a medium saucepan, melt the unsalted butter over medium heat. Ensure it is fully melted and starts to bubble slightly without browning.
- Add the all-purpose flour to the butter, whisking continuously. Cook the mixture for about 2 minutes, allowing it to form a smooth, golden roux with a slight nutty aroma.
- Gradually pour the warm milk into the roux while whisking vigorously to prevent lumps. Continue whisking until the mixture is smooth and begins to thicken, approximately 10 minutes.
- Season the sauce with salt, white pepper, and a pinch of nutmeg. Stir well to combine and taste, adjusting the seasoning if necessary. Cook for an additional 5 minutes on low heat, stirring occasionally.
- Remove from heat and allow the sauce to sit for a few minutes before using. It should have a silky, creamy consistency.
Notes
Nutrition
Common questions
Can I make this sauce ahead and use it through the week?
Yes — it’s actually better suited to batch cooking than to making fresh each time. Store it in the fridge for up to 4 days with plastic wrap pressed onto the surface, and reheat portions as needed with a splash of milk over low heat.
How do I know when the sauce is thick enough?
Dip a spoon in and run your finger across the back — the line should hold clean without the sauce running back over it. If the line fills in, keep cooking and whisking for another 2–3 minutes.
Can I double the recipe without changing anything?
Yes, doubling works without any adjustments to ratios or technique. Use a larger saucepan so the sauce has room to bubble without spilling, and expect the thickening stage to take a few minutes longer since there’s more liquid to heat through.
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