Things do not move fast at Jack-n-Grill. Actually, everything moves fast, but nothing happens quickly. Even with the expansion completed this winter, the wait for a table and the wait for your food can be extreme during peak hours. But should you find yourself in this situation, take a lesson from the regulars who sit with Zen-like indifference to the sweeping passage of the hands of the clock. Just wait, and you will be rewarded by something like the kitchen's vaquero tacos, which are so good that you might never want to eat anything else again. Four tortillas, fried in butter on the flat-top, come laid open on the plate like a taco autopsy, with all of their insides showing. Each one holds a dollop of tender, shredded beef soaked in an incredible smoky-sweet barbecue sauce so dark it's almost black; a sprinkling of diced tomatoes that pair up against the sweetness of the barbecue sauce better than peanut butter does with jelly; just enough melted cheese to weld everything together; and a dainty little curl of sour cream to top things off. It's taco perfection, and if you haven't tried one yet, you don't know Jack.