On a recent trip to OK Natural, a tiny health-food store in Mount Vernon, three hungry friends and I grabbed shrink-wrapped sandwiches from the store's fridge with little enthusiasm. We feared that a chilled vegan BLT might be the kind of food people are fed strictly as punishment, but we were all pleasantly surprised. The prepackaged comestibles OK Natural gets from Sunneen Health Foods in Allentown, Pa., were really quite good. The cold bread didn't hinder my friend's enjoyment of his hummus on rye ($2.79); the vegetarian chicken deluxe ($3.15) won raves. The tempeh bacon in the vegan BLT ($2.79) didn't taste even a little bit like bacon, but it had a nice smoky flavor and was unexpectedly filling. The un-chicken fajita ($2.55) was bland, though a $2.95 tub of tabbouleh was wonderfully tangy. But the best part was the treats--thick, delicious Naked brand smoothies; vegan cookies that are as good if not better than their animal-product counterparts; and Tofutti Cuties mini ice-cream sandwiches that are so dead-on that they'll fool even your most tofu-phobic friends--turning a quickie lunch at a health-food store into a decadent experience.