Step 1: Pat the tri-tip dry with paper towels. Trim any excess silver skin or thick fat, leaving about a 1/4 inch fat cap for flavor.
Step 2: In a small bowl, combine coarse sea salt, coarse black pepper, garlic powder, onion powder (if using), and paprika (if using) to create your Santa Maria style rub.
Step 3: Generously apply the rub all over the tri-tip, pressing it firmly into the meat. Allow the tri-tip to rest at room temperature for at least 30 minutes, or refrigerate for 2-4 hours for deeper flavor.
Step 4: Preheat your grill for two-zone cooking (direct high heat and indirect low heat). Aim for an overall grill temperature of 400-450°F (200-230°C).
Step 5: Place the tri-tip fat-side down over the direct high heat. Sear for 4-6 minutes until a dark, flavorful crust forms. Flip and sear the other side for another 4-6 minutes.
Step 6: Move the tri-tip to the indirect heat side of the grill. Close the lid and continue to cook, turning occasionally, until it reaches your desired internal temperature (125-130°F / 52-54°C for medium-rare, 130-135°F / 54-57°C for medium).
Step 7: In the last 15-20 minutes of cooking on indirect heat, you can baste the tri-tip every 5-7 minutes with a mixture of red wine vinegar and olive oil.
Step 8: Once the tri-tip reaches your desired internal temperature, remove it from the grill and transfer it to a cutting board. Tent loosely with foil and let it rest for 10-15 minutes. This is crucial for juicy, tender steak.
Step 9: Identify the two distinct grain directions in the tri-tip. Cut the roast into two sections if necessary to properly slice each section thinly against its respective grain.
Step 10: Serve immediately with your favorite sides and enjoy your amazing, tender Santa Maria style tri-tip steak!