Cook the dried beans according to package instructions. (Be sure to cook different types of dried beans in separate pots as they will have different cooking times depending on size). After cooking, rinse the beans under cold water. Spread on paper towels to remove any extra moisture and cool completely. In a small stockpot bring 2 quarts of water and 1 tablespoon salt to a boil. Add the green beans and stir to submerge. Blanch until bright green in color and crisp tender, 30 seconds to 1 minute.  Transfer the beans with a slotted spoon to a bowl of ice water to stop the cooking.  Drain the beans and pat dry. In a large mixing bowl or salad bowl whisk the vinegar, mustard, 1½ teaspoons salt and pepper. Slowly add the olive oil in a steady stream, whisking to emulsify. Add the cooked beans, green beans, celery, tomatoes and onion and toss to combine. Serve immediately or refrigerate in an airtight container for up to 2 days.