Combine the freekeh, water and salt in a medium saucepan. Bring to a boil, then reduce the heat to a simmer and cook for approximately 10 to 12 minutes, occasionally stirring, until all the water has been absorbed. Remove from the heat and set aside to cool completely.
Use a fork to mash the black beans until pasty. You can also use a food processor. Add the cooled freekeh, onion, garlic, corn, chilli powder, cumin, paprika, cayenne, salt and black pepper, and mix until all the ingredients are incorporated.
Scoop out about 1/3 cup of the black bean-freekeh mixture and use your hands to shape it into burgers.
Place on a wax paper-lined plate. Repeat with the remainder of the mixture. Cover and put in the fridge for at least 1 hour.
Remove the sliders from the refrigerator and lightly dust the top and bottom of each with a thin coating of fine ground cornmeal. Heat 2 tablespoons of oil in a large cast-iron or heavy-bottomed skillet. When the oil is hot but not smoking, add the sliders to the pan. Cook until golden brown for 5 to 7 minutes. Use a large spatula to flip the sliders over carefully. Cook the other side for another 5 to 7 minutes. Remove the pan from the heat.