In Mexico there is a phrase “comete un taco” (eat a taco) since a homemade taco is a tortilla with anything on it. We buy 1/2 - 1 kilo of (corn) tortillas for a family of four every day or every other day (depending on the food consumed) and it pairs really well with anything. E.g.:

• Eggs, salsa and tortillas
• Beans, cactus, salsa and tortillas
• Beef stew with rolled up tortillas
• Crunchy tortillas (slow comal/gridle heated to make them similar to a tostada, but without frying) with some sour cream, beans, lettuce and salsa
• Cheese quesadilla, generally salsa too (or even hot sauce) - optionally beans and/or some meat
• A taco similar to the one in the picture (maybe minus the cheese, but you could add it of course). These are a little harder to make since they call for specific meats or preparation, so they tend to be more commonly consumed from a vendor specializing in them.
• etc.

Since there is a tortilla in most homemade variations (the taco), everyday can be taco day. The salsa would mostly be served whatever you already have in the fridge, red, green, mild, spicy, etc. Sometimes flour tortillas are used, but corn is more common (and supposedly healthier according to the moms).