Dried kelp (aka kombu) can be found in the Asian section of many supermarkets. Be sure to serve with crusty bread to mop up all that delicious broth!
In a large pot, cover the sausages with water. Bring to a simmer over medium heat. Reduce heat to low. Cook until an instant-read thermometer registers 160° when inserted into the centers of the sausages, about 10 minutes. Transfer to a paper-towel-lined baking sheet and let cool. Cut the sausages crosswise into 2- to 3-inch pieces. Transfer to a container with a lid and cover. Pack with ice in a cooler.
Prepare a grill for medium heat. Place the corn on one side of the grill. Cook, turning occasionally, until charred in spots, about 10 minutes. While the corn grills, on the other side of the grill, add the oil to an extra-large stockpot or Dutch oven or divide it between 2 smaller pots. Add the garlic, crushed red pepper, and fennel seeds. Cook, stirring often, until fragrant, about 1 minute. Add the sliced sausage. Cook until lightly browned, 2 to 3 minutes. Add the wine, stock, and kelp. Add the clams. Stir until combined. Cover and simmer until the clams open, 6 to 8 minutes. (Discard any clams that don’t open.) Remove the pot from heat. Add the butter. Stir until melted. Stir in the herbs. Cut the corn into 2-inch pieces and add to the pot. Ladle the clams, sausage, corn, and broth into shallow bowls. Serve with grilled bread and lemon wedges.