Serves 4
While the vegetables can be cooked for up to 7 hours on low or 4 hours on high, the fish is added to the cooker just about 30 minutes before the end of cooking time. That’s all it needs to get perfectly done.
Prep: 10 minutes
Slow Cook: 6 hours (low) or 3 hours (high)
Total: 6 hours 40 minutes
Trim the fennel bulbs, reserving some of the feathery tops (fronds). Core the bulbs and then chop. In a 4- to 6-quart slow cooker, combine the fennel, serrano chile, garlic, basil, and fennel seeds. Add the tomatoes. Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours.
Turn the slow cooker to high setting if using low setting. Place the fillets on top of the sauce, spacing them evenly. Drizzle the fillets with the olive oil and then sprinkle with the salt and black pepper. Cover and cook until the fish just barely starts to break apart when pulled apart with a fork, 30 to 40 minutes longer. Top servings with bacon and chopped fennel fronds.