This is Tacos Chabelita.  They make tacos de canasta (Tacos in a basket).  These are steamed tortillas that are usually filled with chorizo, pollo, papa, frijol, or beef and are traditional to mejico DF.  In mejico DF these tacos are sold for breakfast.  They are sold in the cloth covered baskets of bicycles and the taquero moves around to select spots of the city until all tacos are sold.  Its common that all of the tacos de canasta are sold before 11am. Tacos Chabelita has one hell of a production.  They sell 1500 tacos in the Plaza Caracol location.  This is a shopping plaza with a grocery store and other consumer driven kiosks so there is quite a bit of traffic.  They have four locations here in the vallarta area and one production kitchen that makes all the tacos.