Cod Fillet with Celeriac Mash & Olive Oil (Low-GI root starch)
By the QuiteRecipes team (Jamy & Kaïna) | Food Service Professional, Early Childhood Expert & Parents
Flaky pan-seared cod over a silky celeriac mash with olive oil — a low-GI root starch swap that tastes indulgent and digests slowly.
Celeriac is the sleeper swap that deserves a fan club: earthy, slightly sweet, and nearly half the carbohydrate of potato, it mashes into something almost whipped. Under a flaky pan-seared cod fillet, with a final drizzle of raw olive oil, it quietly does everything a potato dinner does — minus the glucose rush.
🥄 Ingredients
- 🫗 2 cod fillets (about 150g / 5 oz each)
- 🫗 500g / 1 lb celeriac (celery root), peeled and cubed
- 🫗 1/2 cup (125ml) low-fat milk
- 🫗 1 tablespoon butter
- 🫗 2 tablespoons olive oil, divided
- 🫗 1 garlic clove, crushed (optional)
- 🫗 1/2 lemon
- 🫗 1 tablespoon chopped fresh chives or parsley
- 🫗 Salt and black pepper
Nutrition Facts*
*Nutritional information is an estimate and may vary based on ingredients, brands and portion sizes. Values are provided per serving.
👨🍳 Instructions
Boil the celeriac in salted water 15–18 minutes until completely tender; drain very well.
Meanwhile, pat the cod dry. Heat 1 tablespoon of the olive oil in a nonstick pan over medium-high heat, add the optional garlic, and cook the cod 3–4 minutes per side until opaque and flaking. Squeeze half the lemon over it.
Return the drained celeriac to the pot, add the milk and butter, and mash to a smooth, almost whipped puree. Season.
Serve the cod over the mash, drizzle with the remaining olive oil, and scatter over the chives.
⚠️ Common Mistakes
- ✕
Hammering the cod in the pan past the flake stage — pull it out and let it rest on the plate.
- ✕
Overworking the mash into glue; a few strokes once the butter melts is plenty.
- ✕
Forgetting the lemon — mild white fish needs acid.
🔄 Variations
Swap celeriac for turnip or cauliflower for another low-starch base.
Stir a spoonful of grainy mustard into the mash.
Halibut or haddock stand in for cod beautifully.
🧊 Storage
- 📦
The mash keeps 2 days and reheats with a splash of milk.
- 📦
Cod is best that day; leftover flakes make an excellent cold salad the next.
💡 Chef Tips
Tip 1: Drain the celeriac thoroughly before mashing, or the puree turns watery.
Tip 2: This is the low-GI root-starch move — celeriac at roughly half the carbs of potato, with real fiber behind it.
Tip 3: Pat the cod bone-dry so it sears instead of steaming.
Tip 4: The final drizzle of raw olive oil is the finishing grace; don't skip it.
❓ FAQ
Why celeriac for blood sugar? Celeriac carries a low glycemic load with genuine fiber — the mash tastes indulgent but releases its energy slowly.
Can I skip the milk? Yes — use extra olive oil or a splash of broth for a dairy-free puree.
What if my celeriac turns out stringy? Cube it small and boil until properly soft; a patient mash fixes most texture complaints.
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About the Authors
This recipe and guide was developed, tested, and approved in our home kitchen and daily life. Jamy is a retired Food Service District Manager and Early Childhood Program Manager who spent his career overseeing multi-site restaurant operations, large-scale culinary production, and daycare menu management. Kaïna brings the ultimate real-world test: making sure it brings ease and joy to our kids on a busy weeknight.
Read more about our professional background and philosophy →