In a small bowl, mix together olive oil, garlic powder, onion powder, smoked paprika, salt, black pepper, and cayenne pepper.
Rub this spice mixture all over the tri-tip roast.
Place the tri-tip on a baking sheet and roast in the preheated oven for about 25-30 minutes, or until the internal temperature reaches 135°F (57°C) for medium-rare.
Remove from the oven and let it rest for about 10 minutes before slicing.
Slice the tri-tip thinly against the grain. Toast the sandwich rolls if desired. Layer the sliced tri-tip on each roll, add a generous drizzle of barbecue sauce, top with arugula, red onion, and tomatoes.
Serve the sandwiches warm with extra barbecue sauce on the side.
Keyword baking recipes, beef, California sandwich, sandwich recipe, tri-tip sandwich