In a 9x13-inch baking dish or in a 9x6-inch oval roasting dish, combine the drained and rinsed white beans, shallot, castelvetrano olives, chopped calabrian peppers, 1/4 cup of olive oil, the white wine vinegar, sliced lemons, oregano leaves, 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Toss until well combined.