Rub the entire pork tenderloin with the spice rub and let sit for 20 minutes.
Heat a grill to the 425-450 range and grill the pork on each side for about 5 minutes or until cooked through and internal temperature reaches 145 degrees.
Remove cooked pork to a cutting board and let sit for at least 5 minutes before slicing.
For the Crimini Berry Sauce:
Heat a large skillet over medium heat.
Add the butter, olive oil and onions and saute for about 2-3 minutes.
Add the mushrooms, stir and cook for another 5-7 minutes until mushrooms have released their moisture and are starting to caramelize.
Add the rosemary and stir to combine.
Add the blueberries and blackberries and stir to slightly break down the berries.
Add the raspberries last and give one final light stir (the raspberries are the most delicate of the berries so you don't want to turn them to mush).
Season with salt & pepper to taste and then spoon over the sliced pork.