Prepare mise en place (why: working with everything prepped speeds the cook and prevents overcooking eggs). If you don't have pre-made salsa, make a quick pico: dice 3 medium tomatoes (or 240 g total), 1 small white or red onion (about 60 g) and 1 jalapeño (optional). Mix with 2 tablespoons chopped cilantro, the juice of 1 lime, a pinch of salt and 1/8 teaspoon sugar to round the acidity. Keep refrigerated until assembly.

Warm and season the beans: heat a medium nonstick or cast-iron skillet over medium heat and add 2 tablespoons olive oil. Add the optional minced garlic and cook 20–30 seconds until fragrant (do not brown — garlic burns and turns bitter). Add the 400 g cooked black beans, 1/4 teaspoon ground cumin and 1/2 teaspoon kosher salt; stir and cook 3–4 minutes until beans are heated through and beginning to soften but not falling apart. Smash 1/3 of the beans lightly against the pan with the back of a spoon to create a chunky texture that will cling to tortillas (why: lightly smashing releases starches and thickens the salsa so it won’t slide off the tortillas). Taste and adjust seasoning.

Build the black bean salsa: remove the beans from the heat and fold in 240 g (about 1 cup) of the fresh tomato-onion salsa and 1 tablespoon chopped cilantro. The warm beans will marry with the fresh salsa, slightly cooking the tomatoes and tempering acidity (why: this melds the flavors while keeping the salsa bright). Transfer to a small bowl and keep warm.

Warm the corn tortillas: wipe the skillet clean and return to medium-high. Working in batches (2 tortillas at a time), heat a dry skillet or comal until it’s shimmering but not smoking — 30–45 seconds per side will form faint brown blisters and a bit of char (why: quick, high heat gives the tortillas a toasted, slightly crisp edge that contrasts the soft egg). If you prefer richer tortillas, brush 1/2 teaspoon butter or oil on each side before toasting. Stack warmed tortillas and keep wrapped in a clean towel to stay pliable.

Fry the eggs: in a clean 10–12" skillet, heat the remaining 2 tablespoons oil over medium-low heat until it shimmers gently. Crack 2 eggs per serving (8 total) into a small bowl, then gently slide into the pan. Cook the eggs low and slow for 3–4 minutes until the whites are set but the yolks are still very runny for classic huevos rancheros. For slightly more set yolks, cook 4–5 minutes or baste the eggs with spooned hot oil for 30–45 seconds (why: lower heat cooks the whites through without overcooking the yolks; basting sets the top of the egg while preserving runny yolks). Season with salt and pepper as they cook.

Assemble on the skillet or plates: Arrange 2 warm corn tortillas per person on each plate. Spoon a generous 100 g (about 1/4 of the total) black bean salsa onto each stack, spreading slightly so the tortillas absorb some juices (why: the warm beans soften the tortilla and form a flavorful bed for the eggs). Sprinkle 30 g shredded cheese over the beans so it begins to melt from residual heat.

Top with eggs and finish: Carefully place two fried eggs over each tortilla stack. Scatter the remaining chopped cilantro (1 tablespoon per serving), add avocado slices (1/4 avocado per serving) and spoon an extra tablespoon or two of fresh salsa over the eggs for brightness. Squeeze lime over top, sprinkle with a final crack of black pepper and flaky salt if you have it (why: acid from lime brightens the rich yolks and avocado; finishing salt amplifies all flavors).

Serve immediately with extra tortillas and lime wedges (why: huevos rancheros are best when components are warm; the contrast between hot eggs and cool avocado/salsa is part of the appeal).