In a mixing bowl, combine the olive oil, taco seasoning, and lime juice.

Rub the marinade all over the tri-tip and let it sit for at least 30 minutes.

Preheat your grill to medium-high heat.

Place the marinated tri-tip on the grill. Cook for about 5-7 minutes per side for medium-rare.

Once done, remove the tri-tip from the grill and let it rest for 10 minutes.

Using a sharp knife, slice the tri-tip against the grain into thin strips.

Heat the corn tortillas on the grill for about 30 seconds per side.

Place a few slices of tri-tip on each tortilla and top with onions, cilantro, avocado, and salsa.