Stack the corn tortillas and cut into 1/4″ strips, then cut in half cross-wise.
Heat the oil in a heavy skillet over medium-high heat and fry the strips until crispy, a few minutes, stirring frequently. Drain on paper, lightly salt, and set aside.
Dice the tomato and combine with onion and jalapeño.
Beat the eggs thoroughly.
Melt the butter in the same skillet over medium-heat. Add eggs and cook until half-set.
Add 1/2 cup of the tomato mixture and cook until 3/4 set, stirring frequently.
Add tortilla strips and combine.
Sprinkle with cheese. Cover and remove from heat while you warm tortillas for serving.
Serve as tacos, or alongside refried beans and homefries.