Rebekah Peppler's Pan Bagnat – Cherry Bombe

Ingredients

• 2 medium ripe tomatoes, cut crosswise into ¼-inch [6 millimeters] slices
• Fine sea salt
• ¼ cup [60 milliliters] red wine vinegar
• 2 teaspoons Dijon mustard
• ½ small red onion, finely chopped
• Freshly ground black pepper
• 8 small radishes, finely chopped
• 1 small seedless cucumber or ½ large cucumber, peeled, seeded, and finely chopped
• ½ cup [120 milliliters] extra-virgin olive oil
• 2 baguettes or 4 large, round, crusty bread rolls, halved lengthwise
• Two 5- to 6-ounce [140 to 170 grams] jars tuna packed in olive oil, drained
• ¼ cup [40 grams] Niçoise olives, pitted (or larger black olives, such as Kalamata, pitted and halved)
• 4 large hard-boiled eggs, peeled and thinly sliced lengthwise
• 8 to 12 oil-cured anchovies, drained, if desired