Bring water to a rolling boil.
Add the tomatoes and jalapeños and boil for 20 minutes.
Strain tomatoes and jalapeños reserving 1 pint of the water.
Place tomatoes and jalapeños in a blender with a pinch of salt and blend until a slightly chunky consistency is achieved, adding the reserved water as needed to thin it out.
Salt to taste, add the chopped onions and keep warm.
Heat the oil in a medium sauté pan.
Whip the eggs with a pinch of salt and add to the hot oil.
Cook for 1-2 minutes, flip the omelet and add the cheese and continue to cook until cheese is melted.
Assemble the tacos, top with the warm tomato salsa, garnish with cilantro and serve.