New England Vegan Clam Chowder

Name: New England Vegan Clam Chowder
Ingredients: 1 1/2 tablespoons olive oil; 1 large onion, finely chopped; 4 medium golden or red-skinned potatoes, scrubbed and finely diced; 3 medium carrots, thinly sliced; 2 large celery stalks, diced; 4 cups water; 2 vegetable bouillon cubes; 2 teaspoons salt-free seasoning; 2 cups plain plant-based milk, plus more, as needed; 10.9-ounce container firm or extra-firm silken tofu; 2 cups fresh or thawed frozen corn kernels; 4 to 6 ounces vegan seafood substitute (see brands above recipe box and suggestions in Notes); 1/4 to 1/2 cup chopped fresh parsley, to taste; Salt and freshly ground pepper to taste; Oyster crackers for topping, optional