1. Drain pineapple juice, reserving juice. Combine ½ cup pineapple juice, brown sugar, cumin, cinnamon, thyme, basil, chile powder, red pepper, & garlic in small bowl to create marinade. Mix roast and marinade in a sealable plastic bag or glass marinade dish and refrigerate for 4 hours or overnight.
2. Preheat oven to 350. Cut sweet potatoes into 2 inch slices and cut onion to 8 wedges and pineapple rings into quarters.
3. Remove roast from marinade and rerserve 1 cup. Place roast in rectangular baker. Place veggies and fruit around roast. Pour reserved marinade over roast, sprinkle all with salt and pepper. Cover and bake for 1 hour.
4. Remove lid and continue to cook for 15 minutes or until thermometer reads preferred temp (155 for Medium). Let stand for 10 minutes before carving.