Tofu and Peppers with Spicy Peanut Sauce

packages (14 ounces each) firm or extra-firm tofu, drained well

vegetable oil

soy sauce

medium red bell peppers, seeds and ribs removed, cut into 1-inch-wide strips

smooth peanut butter

fresh lime juice

Asian-style chili-garlic sauce

light-brown sugar

sprigs cilantro, for garnish (optional)