Prepare the marinade: In a bowl, whisk together soy sauce, Worcestershire sauce, red wine or vinegar, olive oil, brown sugar, black pepper, garlic, onion powder, and crushed red pepper.
Marinate the meat: Place the tri-tip in a large resealable plastic bag or container. Pour the marinade over it, seal tightly, and refrigerate for at least 24 hours (up to 48 hours for best flavor). Flip the meat occasionally to ensure even marination.
Preheat the grill: Heat your grill to medium-high. Remove the tri-tip from the marinade and let it come to room temperature (about 20–30 minutes) before grilling.
Grill the tri-tip: Sear the tri-tip over direct heat for 3–4 minutes per side to develop a nice crust. Move it to indirect heat and continue cooking until it reaches your desired doneness (130–135°F for medium-rare).
Rest and slice: Transfer the meat to a cutting board, cover loosely with foil, and let it rest for 10 minutes. Slice thinly against the grain for the most tender bites.