People around here demand a lot from their burritos: They must be too big for a 135-pound person to eat at one sitting. They've got to have plenty of expertly grilled meat or veggies, with fragrant rice and beans. We want freshly made salsas to go with them. Somewhat bizarrely, we want them to have an amazing level of structural integrity, so that we can eat them with one hand. Luckily, the mothership of famous lunch trucks scores high on all counts. El Tonayense's classic Mission-style burritos also have just the right consistency, neither dripping with grease nor dry and crumbling. In the obsessively contested race for best Nor-Cal "food log" experience, we realize that writer Calvin Trillin wears a La Cumbre T-shirt, and El Farolito, Cancun, and Taqueria San Jose have their adherents. But ultimately, locals know that burritos from the Mexican town of Tonaya, Jalisco, are the best. One vehicle sits in front of Best Buy, offering a tasty parting shot after you've salivated over flat screens, but we prefer the one located three blocks south, parked next to slim planter boxes on which to nestle your nalgas.