Until recently, I dreaded the onset of a muffuletta urge. It always entailed a major outlay: airfare to New Orleans and back, $188, taxis to and from the Central Grocery, $35, one muffuletta sandwich, $9.50. Were it not for Sal's Italian Cafe and Grill (1508 Hutchins, 225-4950), on downtown Houston's eastern flank, I'd be insolvent by now. About a year ago, Sal's began making a muffuletta that even New Orleans would raise its hat to. And it costs a mere $7.95. I thank you, Sal. And my accountant thanks you. Who cares if Southwest Airlines isn't pleased? The bun, the mozzarella, the cold cuts.... They're all great. But best of all is the olive salad: chopped black and green olives, celery, onions, herbs, fresh garlic and a little oil and vinegar. Sensational! I'm glad I don't own the Central Grocery. If I did, I'd be very, very worried.