Use a food processor to chop 3 celery stalks, ½ small white onion, and 1 small fennel bulb.
In a large pot, cook mixture in 1 tbsp. olive oil until softened. Add 1 cup dry white wine, 1 cup water, 1 can (14 oz.) fire-roasted diced tomatoes, ¼ tsp. red chile flakes, and ½ tsp. each kosher salt and freshly ground black pepper. Cook, covered, for 10 minutes.
Add 2 cooked crabs (1½ lbs. each), cleaned, quartered, and cracked. Cook, covered, for 5 minutes. Transfer to a serving dish and sprinkle with chopped fresh oregano, flat-leaf parsley, and fennel fronds. Serve with warm, crusty bread.
Print or save recipe: Quick Crab Stew in Fennel-Tomato Broth