Five cloves of garlic and a 28-ounce can of crushed tomatoes make the sauce, and they do it without the fish present. Two and a half hours on Low cooks the raw edge off the tomato and softens the onion into it.
Only then do the fillets go in — thick pieces, nestled into the sauce, cooked just to 145 degrees Fahrenheit. There is no cream and no cheese anywhere in the recipe.
Why This Recipe Works
- Cooking the sauce alone first means the fish is never waiting on a raw tomato base.
- Thick fillets of about six ounces each survive a gentle poach where thin ones would fall apart.
- Sliced rather than crushed garlic stays present in the finished sauce instead of dissolving into it.
- Half a cup of broth is enough to loosen crushed tomatoes without thinning them into a soup.
Ingredient Notes
- Thick white fillets
- Four, about six ounces each — cod, haddock or pollock. Thickness matters more than the species.
- Garlic
- Five cloves, thinly sliced or minced. This is a garlic sauce and the quantity is not a suggestion.
- Crushed tomatoes
- One 28-ounce can. The sauce is meant to read as chunky, so nothing here gets blended.
How to Make It
Cook the sauce
Add the tomatoes, onion, garlic, broth, olive oil, oregano, salt and pepper to the slow cooker. Cover and cook on Low for 2 1/2 hours.
Lay in the fillets
Nestle the thick fish fillets into the chunky tomato-garlic sauce.
Cook to 145F
Cover and cook 25 to 35 minutes more, until the centers reach 145 degrees Fahrenheit and the fish flakes easily.
Serve intact
Serve the fillets intact with plenty of tomato-garlic sauce and parsley.
Keeping the Fillets Whole
The finished dish is judged on whether the fillets are still fillets. These are the four points where that is decided.
Before anything goes in
The fillets are thick, roughly 6 oz each, and of even thickness
A thin tail piece will be overcooked and falling apart by the time a thick centre cut reaches 145F.
At 2 1/2 hours, before the fish
The sauce is chunky and the onion is soft
The fish gets only 25 to 35 minutes. Anything the sauce still needs has to be finished before the fillets go in.
Laying the fish in
Each fillet is nestled down into the sauce and not stirred
Stirring is the single most common way whole fillets become flakes suspended in tomato.
25 to 35 minutes later
The centre of the thickest fillet reads 145F and flakes easily
This is both the safety threshold and the texture threshold - past it the fillets start to break down in the sauce.
Success Tips
- Choose the thickest fillets available. Thin tail pieces overcook while the centres are still coming up.
- Lay the fillets in and leave them. Stirring is what turns whole fillets into flakes.
- Check the centre of the thickest fillet, not the edge.
Serving Ideas
Four servings, each fillet served intact with plenty of the chunky tomato-garlic sauce spooned over and chopped parsley on top.
Frequently Asked Questions
Can I cut the fish into chunks?
No. It stays as whole thick fillets, which is how it is served.
Can I add cream or cheese?
No. Neither belongs in this recipe.
Why does the sauce cook alone first?
Two and a half hours softens the onion and cooks the tomato through. The fish only needs 25 to 35 minutes and cannot wait that long.
