They usually unlock the door at street level a little after 12 noon. Go upstairs and pick any table (most tables were occupied by 1220pm, so I would get there early, and be willing to share your table if necessary).
I went twice while I was in Tunja. Both times the set meal included a big bowl of soup, juice drink, dessert, and a plate with 4 items. The first time I went, I didn't think there was enough protein on the plate. The second time there were beans. Both times the meals were very heavy on starchy items (example: rice, beans, plantains on one plate).
I wish there had been some veggies, such as broccoli, carrots, cauliflower, etc. Anything green would have been nice. This was the only veggie place in town that I could find. The meal of the day is 8.000 pesos as of January 2014.
Cons: Too much starch/carbs on the plate, Food not unique in any way, Flavors nothing special