Pasta Salad with Tomatoes and Peas

INGREDIENTS

• 1 large garlic clove, minced and mashed to a paste with 1/4 teaspoon salt
• 1/2 cup olive oil
• 1/3 cup white-wine vinegar
• 2 teaspoons salt
• 1/2 pound shelled fresh or frozen peas (about 1 1/2 cups), boiled until tender and drained
• 1 pound medium pasta shells
• 1/2 cup shredded fresh basil leaves
• 2 tablespoons water
• 1/2 teaspoon sugar
• 2 teaspoons minced fresh tarragon leaves or 1/2 teaspoon dried, crumbled
• 2 pints red or yellow pear tomatoes or cherry tomatoes or a combination, halved