Garlicky Steamed Mussels and Littleneck Clams with Pesto Toasts

To clean live mussels and clams, scrub under cold running water. Remove beards from mussels. In an 8-quart Dutch oven combine 4 quarts cold water and 1/3 cup salt; add mussels and clams. Soak for 15 minutes; drain and rinse. Discard water. Repeat soaking, draining, and rinsing twice.

In a small bowl combine butter, parsley, tarragon, the minced garlic, the 1/2 teaspoon salt, and the pepper. Use a fork or the back of a spoon to work herbs into butter. Set aside.

In a heavy-bottom 8- to 10-quart pot with a tight-fitting lid heat oil over medium-high heat. Add fennel, onion, and the sliced garlic; cook and stir about 5 minutes or until onion is tender. Stir in wine; bring to boiling. Immediately add mussels and clams. Cover tightly and cook undisturbed for 2 minutes.

Lift lid and, working quickly to retain as much heat in the pot as possible, stir in the herbed butter, tomato, and lemon juice. Cook, covered, over high heat for 4 to 6 minutes more or just until shells open.

Using a large slotted spoon, scoop shellfish into a serving bowl. Discard any mussels or clams that do not open. Pour the cooking liquid over shellfish. Serve immediately with Pesto Toasts for sopping up the liquid.