Sprinkle garlic with salt and mince to combine, then mash to a paste with flat side of chef's knife. In a small bowl, mix paste with paprika, pepper, and 2 tbsp. oil. Spread paste all over tri-tips. Wrap meat in plastic wrap and chill at least 24 hours and up to 2 days.
Preheat oven to 350°. Scrape excess marinade from meat. Heat remaining 1 tbsp. oil in a large, ovenproof frying pan over medium-high heat. Brown tri-tips on one side only, 3 to 4 minutes. Turn meat over in pan; then set in oven and roast until internal temperature reaches 125° for medium-rare, about 20 minutes. Let meat rest, uncovered, on a cutting board 15 minutes.
Meanwhile, make salsa: Put all salsa ingredients in a food processor and pulse several times to combine into a rough sauce.
Slice each tri-tip thinly across the grain, rotating the meat to keep knife perpendicular to the grain (it changes direction on tri-tip). Serve with salsa.
Note: Nutritional analysis is per serving.