Preheat the oven to 400 degrees . In a large, ovenproof skillet, heat 1 tbsp. EVOO over medium-high heat. Season the pork with salt and pepper, add to the pan and cook, turning, until browned all over, 5 minutes. Transfer the skillet to the oven and roast until cooked through but still juicy, 10 to 13 minutes for 2 pieces, or 15 to 18 minutes for 1 whole tenderloin. Let rest for 5 minutes before slicing.
While the pork is roasting, prepare the rice according to package directions.
In a medium skillet, heat 1 tbsp. EVOO over medium heat. Add half of the garlic and cook until fragrant, about 30 seconds. Add the bell peppers and onion and cook until the vegetables are crisp-tender, about 5 minutes. Stir in 1 tbsp. lemon juice and season with salt and pepper.
Scoop the avocado flesh into a small bowl. Mash in the parsley, 1 tbsp. lemon juice, the remaining 1 tbsp. EVOO, remaining garlic and salt and pepper to taste.
Serve the pork with the rice, peppers and avocado mixture.