In a mixing bowl, combine 5 tablespoons of low-sodium soy sauce, 1/4 cup of fresh lemon juice, and 1/2 cup of olive oil. Whisk together until well blended.
To the mixture, add 4 1/2 tablespoons of Worcestershire sauce, 1 tablespoon of minced garlic, 1 1/2 teaspoons of Italian seasoning, 1/2 teaspoon of dried rosemary, 1 teaspoon of black pepper, 1/2 teaspoon of salt, 3/4 teaspoon of onion powder, and 2 1/2 teaspoons of brown sugar. Whisk again until all ingredients are well incorporated.
Place your 2-3 pound tri-tip steak into a resealable storage bag or a shallow container. Pour the marinade over the steak, ensuring it is completely coated. Seal the bag or cover the container.
Refrigerate the marinating tri-tip for at least 2 hours, but ideally, let it sit overnight. This allows all the flavors to penetrate the meat thoroughly.
Preheat your grill or oven. Remove the tri-tip from the marinade, allowing any excess to drip off. Grill or roast according to your preferred method until the internal temperature reaches your desired doneness. Let it rest for about 10 minutes before slicing against the grain.