Look for different sizes, colors, and varieties of tomatoes for the most interesting and delicious salad.
Place beans and 2 1/2 quarts water in a medium stockpot; set over high heat. Bring to a boil, then reduce to a simmer. When beans are almost done, add 1 teaspoon salt. Continue cooking until beans are tender, about 1 hour. Drain beans in a colander. Transfer to a large bowl, and set aside.
Cut leeks in half lengthwise, and place under running water to remove dirt between the layers. Pat dry, and cut leeks crosswise into 1/8-inch-thick slices. Cut fennel bulb in half lengthwise, and remove core. Cut into 1-inch wedges, and cut crosswise into 1/8-inch-thick slices, including stalks.
Heat a medium saute pan over medium-high heat, and add 2 tablespoons olive oil. Add leeks and fennel, and cook until tender, 4 to 5 minutes. Remove from heat, and add to the reserved beans. Add red onion, cucumbers, chives, oregano, and parsley; toss to combine. Add remaining 1/2 cup olive oil and the lemon juice, remaining teaspoon salt, and pepper; toss to combine.
Arrange tomato wedges around the border of a large platter. Spoon the bean mixture into the center of the platter; serve.
Heirloom tomatoes, such as Brandywine, German Striped, and Green Zebra, make a particularly colorful platter, but any combination of tomatoes may be used.