Vegetarian Lettuce Cups — Three Many Cooks

Ingredients

• 2 tablespoons vegetable oil
• 1 medium onion, diced
• 2 garlic cloves, minced
• 1 can (8 ounces) sliced water chestnuts, drained and chopped medium
• 1 package (14 ounces) extra firm tofu, cut into ½-inch cubes
• ¼ cup soy sauce
• ¼ cup ketchup
• 4 teaspoons rice wine vinegar
• 4 teaspoons sesame oil
• 2 teaspoons red pepper flakes
• 2 tablespoons brown sugar