Warm Escarole Salad with Cannellini Beans and Mackerel - Lidia

Ingredients

• 1 pound dried cannellini beans
• 2 fresh bay leaves
• 1 sprig fresh rosemary
• Peperoncino flakes
• 5 tablespoons extra-virgin olive oil
• 3 tablespoons red wine vinegar
• Kosher salt
• 1 small red onion, thinly sliced
• 3 tablespoons capers in brine, drained
• Two 5-ounce cans mackerel fillets in oil, drained
• 2 escarole hearts, coarsely chopped (about 8 cups)