Tuna Nicoise Sandwich | PBS Food

Ingredients

• 1/2 white onion thinly sliced
• 1/2 red onion thinly sliced
• 1/4 cup plus 4 teaspoons extra-virgin olive oil
• 2 tablespoons red wine vinegar
• Coarse salt and freshly ground pepper
• 2 jars (7 ounces each) best-quality tuna packed in olive oil
• 1 tablespoon fresh lemon juice plus lemon wedges, for serving
• 4 small ciabatta rolls split horizontally
• 2 heads Bibb lettuce leaves split horizontally
• 1 1/2 cups nicoise olives pitted
• 8 hard-boiled eggs peeled and thinly sliced