Soak 500g of dried gigantes beans overnight in plenty of water. Drain, cover with fresh cold water, add a pinch of salt, and bring to a boil. Simmer for 45 minutes, until almost tender, and drain.
Meanwhile, preheat the oven to 350°F / 180°C. Bake ½ cup of olive oil, 1 large chopped onion, and 1 small whole garlic clove in a baking dish for about 15 minutes, until softened and lightly colored.
Add the beans, ½ tablespoon of chopped celery, 5 tablespoons of chopped parsley, and ½ cup of hot water. Bake for 30 minutes.
Stir in 400g of canned tomatoes, 1 teaspoon of dried oregano, salt, and pepper. Bake for 50-60 minutes, until the beans are soft and the sauce has thickened.
