Preheat grill. Shuck corn and quarter the onion, leaving root end intact. Brush corn, onion, and whole red pepper with 1 tablespoon olive oil. Sprinkle half of the salt and black pepper over vegetables.
GRILLED CORN CHOWDER: Arrange vegetables on grill and cook, turning with tongs, until charred on all sides, about 15 minutes for bell pepper and corn, and 10 minutes for onion. Meanwhile, baste with remaining olive oil and season with remaining salt and pepper. Remove veggies, and place on a platter to cool.
Cut kernels off corncobs and place in a large pot. Using a paring knife, scrape charred skins off the onion and pepper. Stem, seed, and dice the bell pepper. Trim root end off the onion and dice. Place diced vegetables in a pot with the corn.
Dice potatoes and celery, and stir into pot with flour. Cook vegetables over medium-high heat, stirring frequently, for 2 minutes. Add broth and bay leaf. Bring to a boil, scraping bottom and sides of pot. Reduce heat to low and simmer, uncovered, until potatoes are cooked, about 12 minutes. Remove bay leaf. Stir in half-and-half and Gouda until melted.
GOUDA CROSTINI: Brush bread slices with olive oil, and grill or toast both sides until lightly browned. Top each slice with 1 tablespoon shredded Gouda. Grill for a minute or two until cheese melts and bread is crisp. Garnish soup with crostini.