Prep: 1. In a shallow bowl, season meat with salt, black pepper, and crushed red pepper. Squeeze lime juice over the meat, and turn until evenly coated. 2. Cover, and refrigerate for 30 minutes. 3. Meanwhile, chop cilantro. Dice tomatoes and onions. Set aside for serving. Make: 1. Heat 1 tablespoon oil in a large skillet over high heat. 2. Stir in 1/3 of the beef, and saute for 1 minute. Transfer to serving dish. Repeat with remaining beef. 3. Meanwhile, heat tortillas in the oven or microwave, according to package instructions. 4. Slice avocado right before serving.