Fennel and Radish Salad Stuffed Tomatoes with Raw Mustard Dressing

2 large beefsteak tomatoes (preferably Brandywine variety)
1/4 cup red onion, thinly sliced
1/4 cup cucumber, matchsticks
1/4 cup fennel, matchsticks
1/4 cup radishes, matchsticks

Toss all but tomatoes with:
1 teaspoon raw dijon mustard or prepared dijon mustard
1 Tablespoon raw apple cider vinegar
juice of 1/2 lemon
2 Tablespoons EV olive oil
1 teaspoon raw agave nectar, or to taste
sea salt and pepper to taste

Hollow out tomatoes. Cut out the core and use a melon ball scooper to hollow out tomato innards taking care not to pierce the bottom. (Use reminants in salsa, gaspacho or compost.) Stuff with prepared salad.