Preheat your oven to 425°F (220°C).
Pat the tri-tip dry with a paper towel to ensure a good sear.
Mince the garlic and finely chop the fresh rosemary.
In a small bowl, combine the minced garlic, rosemary, sea salt, black pepper, and half of the avocado oil to create a paste.
Rub the garlic-herb paste evenly over all sides of the tri-tip.
Place the beef in a roasting pan or cast-iron skillet and roast for 15 minutes.
While the beef is roasting, toss the asparagus spears with the remaining avocado oil and a pinch of salt.
Add the asparagus to the roasting pan around the beef and continue roasting for another 10 minutes, or until the beef reaches an internal temperature of 130°F for medium-rare.
Remove from the oven and transfer the tri-tip to a cutting board. Let it rest for at least 10 minutes to lock in the juices.
Slice the beef thinly against the grain and serve alongside the roasted asparagus.