Cod, mashed potatoes, and one block of Bordier Lemon-Olive Oil Butter split three ways across the plate. This is the kind of French weeknight cooking that looks like restaurant food because the components are made separately and assembled at the end: a loose olive oil mash, an emulsified sauce built on shallot and fish stock, and cod fillets cooked in foaming butter. It serves four and nothing in it takes longer than twenty minutes.
At a glance
- Difficulty: Intermediate (Bordier rates it moyen)
- Serves: 4
- Active time: About 30 minutes (our estimate, Bordier does not state one)
- Cook: 20 minutes for the potatoes, 10 minutes for the cod
- Key ingredient: 75 g (2⅔ oz) Bordier Lemon-Olive Oil Butter
Why this works
Cod is lean and mild, which makes it an easy fish to cook badly. It has almost no fat of its own, so anything it is cooked in is what you taste. Bordier's Lemon-Olive Oil butter, made in 2009 for a chef, is churned with lemon-infused extra-virgin olive oil, and it gives cod all three things it needs at once: fat to baste with, acidity to keep it from tasting flat, and the olive oil note that pushes the dish toward the Mediterranean rather than the Atlantic.
The mash is the second half of the argument. Adding olive oil alongside butter and milk gives you a looser, glossier purée than an all-butter mash, closer to a Provençal brandade than to a classic pomme purée. And the sauce is a straightforward emulsion: shallot, fish stock, lemon thyme, reduced by half, then finished off the heat with butter and cream and whisked until it holds. The 75 g block breaks down as 30 g in the mash, 15 g in the sauce, and the remaining 30 g for cooking the fish.
Ingredients
Ask for thick loin-cut cod fillets rather than tail pieces. They hold together better through ten minutes in a pan.
| Ingredient | Metric | US |
|---|---|---|
| Cod fillets | 4 | 4 |
| Bordier Lemon-Olive Oil Butter | 75 g | 2⅔ oz, about ⅓ cup |
| Olive oil | 10 cl | 3⅓ fl oz, a scant ½ cup |
| Potatoes | 500 g | 17 oz, about 1 lb 1 oz |
| Milk | 15 cl | 5 fl oz, about ⅔ cup |
| Whipping or single cream | 10 cl | 3⅓ fl oz, a scant ½ cup |
| Fish stock | 20 cl | 6¾ fl oz, about ¾ cup plus 1 tbsp |
| Shallot, diced | 1 small | 1 small |
| Lemon thyme | 6 branches | 6 sprigs |
| Salt | To taste | To taste |
Method
Step 1: Make the mash
Peel the potatoes and boil them for 20 minutes. Drain them and pass them to a purée. Work in the olive oil, the milk, 30 g (2 tbsp) of the Bordier butter, and salt.
Step 2: Build the sauce
Sauté the shallot, then deglaze with the fish stock and 3 sprigs of lemon thyme. Reduce by half. Off the heat, pull out the thyme, add 15 g (1 tbsp) of the butter and the cream. Season, then whisk until the sauce emulsifies.
Step 3: Cook the cod
Heat the remaining butter until it foams and lay in the cod. Cook for 5 minutes on each side, then serve.
Tips from our kitchen
- Five minutes a side is generous for thin fillets. Bordier's timing suits a thick loin cut. A 1-inch fillet is done in about 4 minutes a side, and a thin tail piece in 3. Cod is cooked the moment the flesh turns opaque and the flakes separate under light pressure. Past that it goes dry and cannot be brought back, so check early.
- Use a ricer, not a food processor. A blender or processor turns potato starch to glue. A ricer or a food mill gives you a smooth purée that will take the olive oil and butter without going gluey.
- Warm the milk before it goes in. Cold milk in hot potato seizes the starch and makes the mash stiff. Bring the milk to a bare simmer first and beat it in while the potatoes are still steaming.
- The sauce lives or dies on the whisk. Off the heat, cold butter, and constant whisking is what turns reduced stock and cream into an emulsion rather than a puddle with fat on top. If it does split, a splash of cold cream and hard whisking will usually pull it back together.
- Only three of the six thyme sprigs are used in the method. The sauce takes three. Use the rest as a garnish, or strip the leaves into the mash. Bordier does not say, so that is our call.
- Dry the fish before it hits the pan. Wet cod steams and will not take on color, and the water knocks the foam out of the butter. Pat the fillets with paper towel and salt them just before cooking, not earlier.
How to serve it
A spoonful of mash, the cod set on top, and the sauce spooned around rather than over so the fish keeps its surface. Nothing else is needed except perhaps some blanched green beans. A Muscadet or a white Burgundy is the obvious bottle. If you are working out which French butter belongs with which fish, our buyer's guide to French butter lays out the differences.
Where to buy Bordier Lemon-Olive Oil Butter in the US
The French Pantry ships Bordier butter across the United States in insulated overnight packaging, straight from the workshop in Brittany.
- Churned Lemon-Olive Oil Butter by Bordier (4.4 oz): hand-churned butter blended with lemon-infused extra-virgin olive oil, created in 2009 for a chef.
For the rest of the hand-churned range, browse the Maison Bordier collection.
Frequently asked questions
How much Bordier butter do I need for this recipe?
One block. Bordier blocks are 4.4 oz (125 g) and the recipe uses 75 g (2⅔ oz), which leaves about 50 g. Buy two blocks if you are cooking for eight.
Can I use a different Bordier butter?
Seaweed butter is a natural fit with cod and turns the dish decidedly Breton. Roscoff Onion butter works well in the mash. Unsalted or Salted butter will cook the fish perfectly well, but you will want lemon zest in the sauce to replace the citrus.
Can I use a different fish?
Haddock, hake and pollock all behave like cod and take the same treatment. A thicker fish such as halibut needs a minute or two longer per side. The mash and sauce are unchanged.
How should I store the butter?
Keep it refrigerated and wrapped, and use it by the date on the pack. Tightly wrapped it freezes for up to three months, though it is at its best fresh.
Does Bordier butter need to be refrigerated?
Yes. Bordier butter is a fresh, hand-churned product and ships cold. Refrigerate it as soon as it arrives.
Can I make any of it ahead?
The mash can be made an hour ahead and kept warm over a pan of hot water. The sauce is best made just before serving, since emulsions do not hold well. The cod should be cooked to order.
Related reading
- How to Choose Your French Butter: A Buyer's Guide
- Bordier Butter: What It Is, Why Chefs Love It, and How to Use It
- Isigny Sainte-Mère: Normandy's AOP Butter & Crème Guide
Recipe and photograph adapted from Maison Bordier, with thanks. The French Pantry is an authorized US retailer of Bordier butter.