Slow-Cooker San Francisco Cioppino with Toasted Sourdough Step-by-step instructions

Before you start

Before you begin, prepare all the ingredients. Scrub the clams and mussels under cold running water, removing any beards from the mussels. Thinly slice the fennel bulb, mince the garlic, and measure the crushed tomatoes and wine.

Have the crab claws ready. The slow cooker insert should be clean and ready to use. If you plan to serve with sourdough, slice the bread and have the garlic clove ready for rubbing.

Instructions

Building the Broth and Adding Shellfish

1. 1Build the Broth Base
   In the slow cooker insert, combine the crushed tomatoes, dry white wine, sliced fennel, and minced garlic. Stir well to distribute the fennel and garlic evenly through the tomato base.
   Look for The broth should be a deep red with visible fennel slices and garlic bits.
   Tip Use a large slow cooker to avoid overcrowding; the shellfish need room to open.
2. 2Add the Shellfish
   Nestle the crab claws, clams, and mussels into the broth, pushing them down so they are mostly submerged. The clams and mussels should be in a single layer if possible.
   Look for Shellfish are nestled into the liquid, with some shells peeking above the surface.
   Tip Discard any clams or mussels that are already open and do not close when tapped.
3. 3Cover and Start Slow Cooking
   Place the lid on the slow cooker and set it to LOW. Cook for 4 hours, until the clams and mussels have opened and the broth has thickened slightly.
   Look for After 4 hours, the broth will be fragrant and the shells will have opened.
   Safe temperature 145°F (63°C) internal temperature (shellfish)
   Tip Resist the urge to lift the lid during cooking to keep the heat steady.

The broth is a vibrant red with fennel slices and garlic floating throughout. The shellfish are nestled into the liquid, and the slow cooker is set to low.

As the first hour passes, the aroma of wine and tomatoes fills the kitchen. The broth should not be boiling; a gentle simmer is ideal. Check that the liquid covers most of the shellfish, adding a splash of water if needed.

Finishing the Seafood

4. 4Add Calamari and Finish
   Once the clams and mussels have opened, gently stir in the calamari rings. Cook for an additional 10–15 minutes on LOW, just until the calamari is opaque and tender.
   Look for Calamari turns from translucent to white and firms up slightly.
   Safe temperature 145°F (63°C) internal temperature (shellfish)
   Tip Do not overcook calamari; it becomes rubbery if simmered too long.
5. 5Discard Unopened Shellfish
   Using tongs, remove and discard any clams or mussels that have not opened after cooking. These are not safe to eat.
   Look for All remaining shells are open and filled with cooked meat.
   Tip Check each shell individually to ensure none are closed.
6. 6Toast the Sourdough
   While the cioppino finishes, toast thick slices of sourdough bread until golden and crisp. Rub each slice with the cut side of a garlic clove while still warm.
   Look for Bread is golden brown with a light garlic aroma.
   Tip Use a toaster or place under the broiler for 1–2 minutes per side.

After four hours, the clams and mussels have opened, releasing their briny liquid into the broth. The crab claws are bright orange and heated through. The calamari rings, added now, turn opaque and tender within minutes.

The broth has thickened slightly and smells intensely of the sea. Discard any unopened shells. The sourdough is toasted and rubbed with garlic, ready for serving.

Serving the Stew

7. 7Ladle and Serve
   Ladle the cioppino into warm bowls, making sure each serving gets a portion of broth, crab, clams, mussels, and calamari. Serve immediately with the garlic-rubbed toasted sourdough for dunking.
   Look for Steaming bowls of cioppino with shellfish and a rich red broth.
   Tip Provide small bowls for discarded shells and plenty of napkins.

The cioppino is ladled into bowls, each with a generous portion of broth and a mix of shellfish. The toasted sourdough is passed around for dunking. The broth is rich, tomatoey, and fragrant with fennel and wine. The shellfish are tender and juicy. The meal is best enjoyed immediately, with plenty of napkins and small bowls for shells.

Common mistakes

A common mistake is overcrowding the slow cooker, which can prevent the shellfish from opening evenly. Use a large slow cooker and arrange the shellfish in a single layer if possible.

Another mistake is cooking the calamari for too long; it turns rubbery. Add it only during the last 10–15 minutes. Also, do not skip the step of discarding unopened shells—they are not safe to eat.

How to tell it’s done

The cioppino is done when the clams and mussels have opened wide, the crab claws are heated through, and the calamari is opaque and tender. The broth will have deepened in color and thickened slightly. The internal temperature of the shellfish should reach at least 145°F (63°C). Discard any shellfish that remain closed. The stew should be piping hot when served.

• Shellfish: 145°F (63°C) in the thickest part