In a large mixing bowl, whisk together the olive oil, red wine vinegar, lemon juice, and Worcestershire sauce.

Add the minced garlic to the marinade and stir well to combine.

Sprinkle in the oregano, black pepper, kosher salt, and red pepper flakes. Whisk until the salt dissolves and spices are evenly distributed.

Taste the marinade and adjust seasoning with more salt, pepper, or lemon juice if needed.

Pat the tri tip dry with paper towels and trim any excess fat.

Place the tri tip in a resealable plastic bag or shallow dish and pour the marinade over it, ensuring the meat is fully submerged.

Seal the bag or cover the dish and refrigerate for at least 4 hours or overnight.

Remove the tri tip from the refrigerator 30 to 45 minutes before cooking to bring it closer to room temperature.

Preheat your grill to medium-high heat (400–450°F) or heat a cast iron skillet over medium-high on the stovetop.

Remove the tri tip from the marinade, letting excess drip off, then sear for 4 to 5 minutes per side until internal temperature reaches 130–135°F for medium-rare.

Let the cooked tri tip rest for 10 minutes before slicing against the grain and serving.