Make the miso sauce. Combine miso, brown sugar, tamari, ginger and sesame oil in a small jar or bowl.
Pat the salmon filets dry and check to make sure all the pin bones have been removed.
Brush the miso sauce on the salmon and let it stand while you prepare the vegetables.
Snap off or cut away any woody stems from the asparagus, trim the sugar sanp peas and slice the red bell pepper into thin strips. Toss with 2 teaspoons of olive oil and sprinkle lightly with sea salt and freshly ground pepper.
Cut two pieces of heavy-duty aluminum foil (or 4 pieces of regular foil) about 24 inches long. Line with a piece of parchment paper if you don't like aluminum touching your food.
In each packet, place the salmon fillet skin side down on the paper, then arrange the vegetables beside it.
Fold the sides of the foil up and over the salmon and vegetables until the two sides meet, then seal by folding that edge over 2 or 3 times. Fold the top and bottom edges over 2 or 3 times to make a sealed pouch.
Place the packets on a baking sheet to transport them to your outdoor grill. Slide them onto the grates, close the lid and cook for 10 minutes. Cooking time will depend on the thickness of the salmon fillets. Remove from the grill when the internal temperature of the thickest part of the salmon is 135°F. to 140°F. The salmon will continue to cook as it rests and should be perfectly cooked at 145°F.
Carefully open the foil packets, avoiding the hot steam. Garnish with freshly snipped chives or green onions or sesame seeds. Eat right from the packet or transfer the meal to a plate.