Monkfish and Clam Bourride

Name: Monkfish and Clam Bourride
Ingredients: 6 small (1 1/2- to 2-inch) red potatoes (3/4 pound); 2 large leeks (white parts only), cut crosswise into 1/4-inch-thick slices; 1 (1-pound) piece monkfish fillet, cut into 2-inch chunks; 3 tablespoons extra-virgin olive oil; Slow-braised tomatoes; 1 large fennel bulb (sometimes called anise), stalks discarded and bulb halved lengthwise, cored, and thinly sliced lengthwise; 1 cup thinly sliced shallots (4 medium); 4 garlic cloves, 3 thinly sliced and 1 halved crosswise; 24 small hard-shelled clams (2 pounds) such as littlenecks (less than 2 inches wide), scrubbed well; 1/2 cup dry white wine; 1/2 cup water; 1 teaspoon dried hot red pepper flakes; 1 teaspoon finely grated fresh lemon zest; 8 fresh basil leaves, chopped; 2 tablespoons chopped fresh parsley; 4 (3/4-inch-thick) slices crusty bread (about 4 inches wide), toasted; Accompaniments: aïoli and green olive tapenade; Garnish: 8 whole fresh basil leaves