In a blender or food processor, combine first 5 ingredients and blend until smooth.
Add olive oil to the blender and process again until the mixture is creamy. Season with salt and pepper.
Trim and pat the steak dry with a paper towel.
Pour marinade over steak and turn to coat. Cover and place in fridge for at least 30 minutes, and up to 8 hours.
Preheat Traeger grill to 225°. When grill is hot, place steak in the center of the grill and close the lid.
Grill steak until internal temperature reaches about 115°.
While steak is grilling, toss pineapple spears in brown sugar.
When steak reaches 115° internal temperature, remove it from the grill and pat it dry with a paper towel. Season with salt, pepper and garlic.
Meanwhie crank up the temperature of your grill to the highest setting possible for searing.
When grill is super hot, sear the steak for about 60 seconds per side until internal temperature reaches about 130° and outside has grill marks or a nice char.
Remove steak to plate and tent with foil.
On the same hot grill, place pineapple spears on the grill and cook for 3-5 minutes, turning occasionally, until golden and carmelized.
In a bowl, combine sauce ingredients and roughly chop the pineapple spears. Combine all ingredients together and season to taste.
Slice the steak against the grain and serve with pineapple sauce.