Sandwich Nicoise (Pan Bagnat) | Tante Marie's Kitchen

Ingredients

• 1/4 white onion, halved and thinly sliced
• 1/8 small red onion, halved and thinly sliced
• 2 tablespoons extra-virgin olive oil, plus additional for drizzling
• 1 tablespoon red-wine vinegar
• coarse salt
• freshly ground black pepper
• 4 to 6 oz. good quality tuna, packed in olive oil
• lemon juice
• 1 baguette
• 1 head soft, green lettuce
• 4 medium-sized red tomatoes, sliced
• 4 hard-cooked eggs, sliced
• 12 to 24 anchovies
• 1/2 cup Nicoise olives, pitted