I guess this could carry over to Mexican food:
Do you have self help condiments? Tacky Squeeze bottles of hot chili sauces/salsas?
Sometimes the customers like "making" their own meal.
I found in some restaurants that the sauce is so good, that the food just becomes a vehicle to be able to eat some of that sauce.
You must take note at Phillipe's. They give you meat on bread... soggy if you want it. Other than that, you dress up your sandwich yourself.
Many years ago, prior to the wrap craze I wanted to open (I had better sense) a small place and call it Ethnix or It's a Wrap. It was going to be simple:
Choice of meat: chicken, pork, beef, pastrami, hot dog, tofu, grilled, marinated eggplant, etc...
Choice of wrapper: roll or flour tortilla
Filler: beans, rice or some sort of pickled thing
and then to make it mine... or theirs....
Barbecue, Curry, Sweet and Sour, Harissa, tahini, Teriyaki, Peanut-Coconut, Hot red CHILE sauce, hot green CHILE, Hot, brown and yellow mustards, etc.
The plan: Give them a basket with an open bun or tortilla, covered with their choice of meat.
Have a station with bottles of the sauce and let the customer make their own.
Just an idea I had when I was young enough and able enough and smart enough to never do it.
I always thought it would be simple and simple "should" be good.