Prep ingredients: drain and rinse both cans of black beans and set in a bowl; finely dice the onion; mince the garlic; shred the cheddar if not pre-shredded; halve, pit and slice the avocado; and juice the lime. Having everything ready keeps the cooking tight and prevents overcooking any single element.

Make the lime-cilantro yogurt: in a small bowl stir together the Greek yogurt, juice of 1 lime, half the chopped cilantro (reserve the rest for garnish), a pinch of salt and pepper. This bright, cool sauce will balance the smoky, warm flavors and add moisture without oil — mixing it early gives the flavors time to marry.

Sauté onion and garlic to build flavor: heat 2 tablespoons olive oil in a large skillet over medium heat until shimmering. Add the diced onion and a pinch of salt, and cook 5–7 minutes until softened and beginning to caramelize. Add the garlic and cook 30–45 seconds more until fragrant. Gently caramelizing the onion brings out natural sweetness that contrasts the smoky spices — don't rush this step with high heat or the onion will brown unevenly.

Bloom the spices: lower the heat to medium-low, stir in the ground cumin, smoked paprika and chili powder, and cook 20–30 seconds so the spices toast and release their essential oils. Toasting spices in fat (oil) instead of adding them to dry beans amplifies their aroma and flavor.

Add beans and braise: add the drained beans to the pan along with 1/4 cup water or stock and the remaining 1/4 tsp salt and 1/4 tsp black pepper. Use a sturdy spoon or fork to gently press and partly mash about half the beans in the pan — this creates a creamy base while still keeping whole beans for texture. Simmer 3–5 minutes until heated through and slightly thickened. The light mashing gives body (so you don't need extra cheese or fat) and helps the filling bind inside the tortilla.

Adjust seasoning and finish: stir in the lime juice and taste; adjust salt, pepper, or a pinch of chili powder for heat. Stir in the reserved cilantro off the heat. Fresh acid (lime) brightens the whole dish and cilantro adds herbal lift.

Warm the tortillas: wrap the 4 flour tortillas in a damp paper towel and microwave 20–30 seconds, or warm individually in a dry skillet over medium for 20–30 seconds per side. Warming makes tortillas pliable and prevents them from cracking when you roll — cool tortillas tear and leak filling.

Assemble burritos: lay a warm tortilla on a flat surface. Spoon about 3/4 cup of the bean mixture down the center, sprinkle about 1/4 cup shredded cheddar, add a few avocado slices (about 1/4 of the avocado per burrito), and drizzle 2 tablespoons of the lime-cilantro yogurt. Add hot sauce or salsa if you like. Leaving space at the edges and not overfilling makes rolling easier.

Fold and toast for finish: fold the sides in, then roll the burrito tightly from the bottom. Place seam-side down in a hot, lightly oiled skillet over medium heat and toast 1–2 minutes per side until golden and the cheese melts. Toasting seals the seam and creates a crunchy exterior that contrasts the creamy inside.

Serve: remove from the pan, let rest 1 minute (the filling will be very hot), slice in half if desired, and garnish with remaining cilantro and lime wedges. Serve immediately so the tortilla is crisp and the yogurt is cool against warm beans.