In a large pot over medium heat, cook the bacon, stirring often, just until crispy (bacon varies in cooking time depending on how it’s prepared and how thick it is, so keep a sharp eye), 3–6 minutes. Pour off all but about 1 tablespoon of bacon fat. Add the celery, fennel and onion and cook, stirring occasionally, until the celery is translucent, about 5 minutes. Stir in the thyme and bay leaf. Add the beer and deglaze the pan, stirring to loosen any browned bits from the pan bottom, and cook until the liquid is reduced by about half, about 4 minutes. Add the cold fish stock, potatoes, clams and bouquet garni (tying the herb bundle to the pot handle so it’s easier to retrieve later). Stir to combine. Bring the chowder to a boil over high heat, then reduce the heat to medium-low and simmer uncovered until the potatoes are just tender, about 6 minutes. Remove from the heat. Stir in the salt and fish sauce. Add the kombu and let cool, then refrigerate overnight to develop the flavors.

To serve, bring the soup to a simmer over medium-low heat. Discard the bouquet garni and kombu. Taste and adjust the seasonings with salt, pepper and lemon juice. Divide among serving bowls. Garnish each serving with chopped parsley and serve with lemon wedges. Serve hot. Makes 2 quarts. Serves 4–6.