1⁄2 cup sun-dried tomatoes2 tablespoons olive oil1 1⁄2 cups chopped onions2 garlic cloves coarsely chopped2 teaspoons salt2 teaspoons ground fennel seeds1 small fennel bulb, diced (about 2 cups)1 cup diced carrots1 1⁄2 cups diced potatoes2 teaspoons dried thyme or 1 tablespoon fresh1⁄4 teaspoon ground black pepper3 cups chopped fresh tomatoes or one 15-ounce can diced tomatoes3 cups cooked white beans (two 15-ounce cans drained)4 cups water or vegetable stock5 or 6 cups loosely packed chopped collard greens3 tablespoons fresh lemon juice