Sheet Pan Garlic Butter Cod Loin

3 peppers (different colors – sliced)1 red onion (sliced)2-3 potatoes (diced)1 pound asparagus (trimmed)4 tablespoons olive oil (divided)Kosher salt and freshly ground black pepper (to taste)4 pieces cod loin1 1/2 cups cherry tomatoes3-4 tbsp garlic and herb...