Heat a medium skillet over medium. Add oil, then stir in onion and garlic, and cook, stirring occasionally, until softened, about 4 minutes. Stir in jalapeño and cook until softened, about 2 minutes more.
Crumble chorizo into the pan; sprinkle with chili powder, cumin and black pepper and stir to combine. Cook, stirring occasionally and breaking up chorizo into small chunks, until chorizo is cooked through, 4 to 5 minutes.
Add eggs, pouring them gradually into the pan in a circular motion. Stir into chorizo mixture and cook until eggs are just set. Reduce the heat to the lowest setting to keep chorizo mixture warm while you heat the tortillas.
Heat a separate pan (or a comal, if you have one) over medium. Add tortillas to the pan one by one, heating them through. (Flip each tortilla when it begins to puff up on each side, then remove when warmed.)
Fill a tortilla with chorizo filling, then add cheese to taste and roll the taquito until it’s shut. Repeat until you’ve used the remaining filling and tortillas. Serve with salsa, if you like.
