Fire up your smoker to 225°F (107°C). If using a charcoal grill, ensure you are set up for 2-zone indirect cooking. Place wood chips on coals or in wood tray.
While the smoker heats up, prepare the tri-tip by trimming any excess fat or silver skin from the meat surface
Next, prepare the dry rub. In a small bowl, combine the salt, black pepper, smoked paprika, garlic powder, onion powder, ground cumin, chili powder, and brown sugar. Use a fork to remove or break down any lumps that may have formed.
Apply a thin layer of olive oil to the tri-tip, covering the entire surface. Next, apply the dry rub to the tri-tip, covering all sides.
Once the smoker has hit 225°F, place the tri-tip on the smoker grates. If using a charcoal grill, ensure you place the tri-tip on the indirect side of your 2 cooking zones.
Smoke the tri-tip to an internal temperature of 130°F (54°C), about 2 hours
While the tri-tip is smoking, prepare the fresh salsa. In a medium bowl, combine diced tomatoes, red onion, jalapeno, cilantro, and lime juice. Season with salt and pepper to taste. Set aside to let the flavors meld.
When the tri-tip has reached the desired internal temperature, remove it from the smoker and let it rest for at least 15 minutes
While the tri-tip is resting, warm the tortillas in a dry skillet in your smoker or grill. Keep them warm by placing each tortilla between paper kitchen towels.
Slice the tri-tip against the grain into thin strips
To assemble the tacos, serve the sliced tri-tip into each tortilla and top with fresh salsa, avocado slices, sour cream, and crumbled queso. Garnish with fresh cilantro leaves and a squeeze of lime. Serve immediately.