Vegetable Bouillabaisse with Rouille

Name: Vegetable Bouillabaisse with Rouille
Ingredients: 2 tablespoons grapeseed oil; 1 onion, cut into chunks; 1 celery stalk, cut into chunks; 3 garlic cloves, coarsely chopped; 2 bay leaves; 2 fresh thyme sprigs; ½ teaspoon whole black peppercorns; Kosher salt and freshly ground black pepper; ½ cup dry white wine, such as Sauvignon Blanc; Kombu stock (recipe follows); 1 teaspoon saffron threads; ¾ pound small oyster mushrooms, stemmed; 4 artichoke hearts, halved (or a 15-ounce can); 1 15-ounce can diced tomatoes; 2 leeks, chopped; 1 large fennel bulb, trimmed, halved, cored, and chopped; 3 garlic cloves, minced; 4 fresh flat-leaf parsley sprigs, chopped; Finely grated zest and juice of 2 oranges; 2 tablespoons Pernod; 1 teaspoon herbes de Provence; Rouille (recipe follows); Toasted crusty baguette slices, for serving