Step 1- Sauté the Onion and Garlic
In a large pan with a lid, heat the oil over medium heat. Add the chopped onion and cook until translucent, about 3 minutes. Add the garlic and cook for another minute, stirring so it doesn't scorch.
Step 2- Bloom the Spices
Stir in the cumin and smoked paprika, coating the onion and garlic completely. This step only takes about 30 seconds, but it wakes up the spices and gives the whole filling way more depth than just dumping them in later.
Step 3- Simmer the Beans
Add the black beans, corn, water, and tomato paste to the pan. Mix everything well, cover with the lid, and let it simmer over low heat for 5 to 7 minutes, stirring occasionally so nothing sticks to the bottom.
Step 4- Stir in the Rice and Lime
Turn off the heat and add the cooked rice, lime juice, and cilantro if you're using it. Stir until fully combined, then season with salt and pepper to taste. This is your last shot to adjust the flavor before it gets wrapped up, so taste generously.
Step 5- Soften the Tortillas
Stack the tortillas on a microwave-safe plate, cover with a damp paper towel, and microwave for 10 seconds. Flip the stack and microwave for another 10 seconds. Skipping this step is basically guaranteeing a cracked, torn tortilla, so don't skip it.
Step 6- Roll the Burritos
Lay out a tortilla and add 1 cup of filling near one edge. Fold that edge over the filling, tuck in the sides, and roll it up tightly into a burrito. Repeat with the remaining tortillas until you've got 6 ready to go.
