1/4 cup fresh lime juice (from about 3 limes)
2 tablespoons Maggi liquid seasoning (or use 1 tablespoon soy sauce plus 1 tablespoon Worcestershire sauce)
6 cloves garlic, minced
3 serrano chile peppers, seeded and minced
Kosher salt and freshly ground pepper
1/2 cup olive oil
3 to 4 pounds beef brisket, trimmed and cut into 3 large pieces
3 tablespoons vegetable or olive oil
1 large onion, diced
1 large red bell pepper, diced
1 cup low-sodium beef broth
1 28-ounce can diced tomatoes
1/2 teaspoon dried oregano
16 crisp corn tostada shells
Shredded lettuce, diced avocado, fresh salsa and queso fresco, for topping
Mexican crema or sour cream and lime wedges, for serving