Pat the beef loin tri tip roast dry with paper towels.
In a small bowl, mix kosher salt, black pepper, garlic powder, onion powder, and smoked paprika.
Rub the spice mixture evenly over all sides of the tri tip roast.
Heat olive oil in a large skillet over medium-high heat.
Sear the tri tip roast for 3 to 4 minutes on each side until browned.
Place the sliced onion and minced garlic in the bottom of the crock pot.
Set the seared tri tip roast on top of the onions and garlic.
Pour beef broth over the roast.
Add fresh rosemary and thyme sprigs on top of the roast.
Cover the crock pot and cook on low for 6 hours, or until the roast is tender and reaches an internal temperature of 135°F (medium rare) to 145°F (medium).
Remove the roast from the crock pot and let it rest for 10 minutes before slicing against the grain.
Serve with the cooked onions and pan juices from the crock pot.