In a large resealable bag, combine soy sauce, Worcestershire sauce, water, lime juice, minced garlic, minced chili, salt, and pepper. Shake to mix.
Add skirt steak to the marinade, ensuring each piece is coated. Seal and refrigerate for 8 hours or overnight.
Bring steak to room temperature. Remove from marinade, pat dry, and discard marinade.
Heat 1/4 cup oil in a large pan over medium-high heat. Sear steak on all sides. Set aside.
In the same pan, sauté onions, bell peppers, garlic, and optional chilis for 5 minutes.
Pour in beef broth and diced tomatoes. Add oregano, salt, and pepper. Return steak to pan, bring to a boil, then simmer covered for 2 hours until tender.
Transfer steak to a cutting board to rest for 15 minutes.
Reduce the remaining liquid in the pan until thickened.
Shred steak and return to the pan to reheat.
Warm tortillas and fill with steak mixture. Serve with optional toppings.