Set a heavy skillet or comal over medium-high heat until hot, about 2 minutes, and measure 0.5 cup vegetable oil; set the oil aside to use throughout.
Add the Roma tomatoes, serrano chiles (trim stem ends), white onion (in wedges), and garlic to the dry skillet; char, turning occasionally, until blistered and softened with blackened spots, 8–10 minutes.
Transfer the charred vegetables to a blender; add the cilantro and blend until mostly smooth, 30–45 seconds.
Heat 1 tbsp of the reserved oil in a saucepan over medium heat until shimmering, about 1 minute; pour in the blended mixture and simmer, stirring occasionally, until slightly thickened, 8–10 minutes; stir in the kosher salt and keep the salsa warm over low heat.
Warm 1 tbsp of the reserved oil in a skillet over medium heat until shimmering, 1 minute; add the canned pinto beans (with their liquid) season with a couple pinches of salt and cook, mashing, until spreadable and steamy, reduce heat to low to keep warm.
In a small pan, add 0.25 cup of the reserved oil and heat over medium-high until hot, 1–2 minutes; fry the corn tortillas one at a time, turning once, until pliable with lightly crisp edges, 30–45 seconds per side; drain on paper towels and keep warm.
Push beans aside and add 1 tbsp of the reserved oil to the skillet, increase heat to medium-high; crack in the large eggs and cover pot, cook sunny-side up until whites are just set and edges crisp, 2–3 minutes.
Place 2 fried tortillas on each plate; spread a layer of the warm mashed beans on each; top each tortilla with one egg; spoon hot salsa over the eggs and tortillas and serve immediately while hot.
Finish with queso fresco, avocado, fresh cilantro leaves, and lime wedges as desired; serve at once while the tortillas remain crisp.