For the tri-tip:
1 1/2 teaspoons garlic powder or granulated garlic
1 1/2 teaspoons kosher salt
1 1/2 teaspoons coarsely ground black pepper
1 (about 2 1/2-pound) beef tri-tip roast
2 tablespoons vegetable or canola oil
Flaky salt, for sprinkling (optional)
For the relish:
1/3 medium English cucumber (4 to 5 ounces)
1 medium roma or plum tomato (about 4 ounces)
1 clove garlic
6 sprigs 6 sprigs fresh parsley
1/2 medium lemon
1 tablespoon olive oil
1/4 teaspoon kosher salt, plus more as needed
1 ripe but firm large California Avocado (about 8 ounces)
Make the tri-tip:
Stir 1 1/2 teaspoons granulated garlic, 1 1/2 teaspoons kosher salt, and 1 1/2 teaspoons coarsely ground black pepper together in a small bowl. Pat 1 (about 2 1/2-pound) beef tri-tip roast dry with paper towels. If there is any silver skin on the surface, trim it off (here’s how). Rub all over with the garlic mixture. The tri-tip can be cooked immediately or transferred to a plate and refrigerated uncovered for up to 8 hours.
Arrange a rack in the middle of the oven and heat the oven to 400ºF. If the tri-tip has been refrigerated, let it sit out at room temperature while the oven heats.
Heat 2 tablespoons vegetable oil in a large oven-safe or cast iron frying pan (at least 12 inches wide) over medium-high heat until shimmering. Add the tri-tip smoother-side down and press down on it briefly so it has good contact with the pan. Cook undisturbed until well-browned on the bottom, about 3 minutes. Flip the tri-tip.
Transfer the pan to the oven and roast until an instant-read thermometer inserted into the thickest part of the tri-tip registers about 125ºF for medium, 20 to 30 minutes. Meanwhile, start the relish.
Make the relish:
Prepare the following ingredients, adding each to the same medium bowl as you complete it: Dice 1/3 medium English cucumber (about 1 cup). Core and dice 1 plum tomato (generous 1/2 cup). Mince 1 garlic clove. Pick and finely chop the leaves from 6 fresh parsley sprigs until you have 2 tablespoons. Squeeze the juice from 1/2 medium lemon (about 1 1/2 tablespoons).
Drizzle with 1 tablespoon olive oil, season with 1/4 teaspoon kosher salt, and toss to combine.
When the tri-tip is ready, transfer to a clean cutting board and let rest 10 minutes (tent loosely with aluminum foil if the kitchen is cold). Meanwhile, halve, pit, peel, and dice 1 ripe but firm large California Avocado (about 1 cup). Add to the relish and gently fold to combine. Taste and season with more kosher salt as needed.
Cut the roast in half crosswise at the center point. Cut each half across the grain into slices about 1/2-inch thick. Sprinkle the slices with flaky salt if desired and serve topped with the California Avocado relish.
Roasted Tri-Tip Steak with California Avocado Relish