Heat a grill to high heat.

To make the BBQ sauce, place the tomato sauce, sweetener, vinegar, garlic, onion salt, and liquid smoke in a small bowl. Stir well. Taste and adjust sweetness to your liking. Pour half of the sauce into another bowl and set aside for serving.

Pat the tenderloin dry and season well with salt and pepper.

Pat the tenderloin dry and season well with salt and pepper.

Place the loin onto the hot grill and cook for 10-14 minutes, rotating every 3 minutes to cook all sides. Baste with 1/2 of the bbq sauce. Cook until internal temperature is 145 degrees F.

Remove from grill and place onto a serving platter. Allow to rest for 10 minutes. Slice into 1 inch thick slices. Serve with the reserved BBQ sauce.

Store extras in an airtight container in the fridge for up to 5 days. To reheat, place a slice on a rimmed baking sheet in the oven at 350 degrees F for 5 minutes or until heated through.