Preheat an outdoor grill to medium-high or an oven to 400 degrees. Scrub potatoes well then pat dry using a kitchen towel. Cut potatoes into 1" cubes and place in a large mixing bowl. Dice onion and bell pepper into large 1" pieces.
Drizzle veggies with olive oil and season with salt. Toss to coat completely in oil and distribute salt. Place ¼ of the veggie mixture into the center of one sheet of foil then add ¼ of the smoked sausage on top of the veggies.
Fold long sides of foil up and over sausage mixture and bring edges together. Roll the foil together, moving downward until you’re about 1"–2" from top of sausage mixture. Fold both short ends together to seal the packet, but make sure to leave enough space inside the packet for steam expansion.
Place packets directly on grill or on a baking sheet in the oven. Grill 20–25 minutes or bake 30–35 minutes in the oven or just until the potatoes are tender. Remove from grill or oven and allow packets to rest for 5 minutes. Carefully open packets to let steam escape before digging in.
One Last Thing
This dish is great for camping—just place the foil packets on the camp fire coals!