Heat oil in stockpot over medium heat until hot. Place beef Brisket in stockpot; brown evenly. Remove Brisket; season with salt and black pepper.
Add onion and garlic to stockpot; cook and stir 4 to 5 minutes or until onion is crisp-tender. Return Brisket, fat-side up, to stockpot. Add beer and 1 cup salsa; bring to a boil. Reduce heat; cover tightly and simmer 2-1/2 to 3 hours or until Brisket is fork-tender.
Remove Brisket; keep warm. Skim fat from cooking liquid; bring to a boil. Cook 18 to 20 minutes or until reduced by half. Stir in remaining 1/4 cup salsa. Meanwhile, trim fat from brisket. Carve diagonally across the grain into thin slices. Return beef to cooking liquid and heat through. Serve beef in tortillas. Garnish with Toppings, as desired.
Nutrition information per serving: 321 Calories; 72 kcal Calories from fat; 8 g Total Fat; 2 g Saturated Fat; 4 g Monounsaturated Fat; 93 mg Cholesterol; 353 mg Sodium; 22 g Total Carbohydrate; 3 g Dietary Fiber; 35 g Protein; 3 mg Iron; 8.2 mg NE Niacin; 0.3 mg Vitamin B6; 2.3 mcg Vitamin B12; 7.7 mg Zinc; 32.8 mcg Selenium; 122.4 mg Choline;