A burrito de huevo is a breakfast built from scrambled eggs and a flour tortilla, and the two need each other for reasons of texture as much as flavor. Soft scrambled eggs are loose and prone to falling apart on a fork; a warm flour tortilla is a neutral, flexible container looking for a soft filling to justify it. Wrapped together, the eggs gain a structural wall and the tortilla gains a rich, custardy core. The egg is the binder of the whole build, which is why it tolerates so many additions without losing its identity. Chorizo, machaca, beans, potato, or cheese all fold into the curd rather than competing with it.
The craft is in the scramble and the moisture. Eggs should be cooked low and pulled while still slightly soft, because they keep setting from residual heat and dry eggs make a dull, crumbly burrito. If chorizo goes in, it is usually cooked first and its rendered fat partly drained, so the eggs are seasoned by it without swimming in grease that would soak the wrap. If machaca goes in, the dried shredded beef is rehydrated and cooked dry before it meets the egg. The point in every case is a filling that is moist but cohesive, not wet. The tortilla is warmed on a comal until it flexes, the egg laid in a tidy band down the center, the sides folded in, and the cylinder rolled tight while everything is still warm so it holds. A common failure is overstuffing a soft filling into too small a tortilla, which splits at the first bite. A clean build keeps the egg disciplined and the wrap sealed so it eats evenly.
Add potato and you slide toward the potato and egg burrito, a heartier breakfast that deserves its own article rather than being crowded in here. Lean fully on chorizo and the result is a burrito de chorizo con huevo, where the sausage leads and the egg supports, a different balance that deserves its own article rather than being crowded in here. Fold in dried shredded beef instead and you reach burrito de machaca, a Northern Mexican standard that deserves its own article rather than being crowded in here.