Paling in ’t groen — eel in green sauce — is one of the oldest dishes in Belgian cuisine and one of the least known outside of it. It originated along the rivers and waterways of the Scheldt basin, particularly around Mechelen and the towns between Ghent and Antwerp, where freshwater eel was abundant. The green sauce is made from a mixture of fresh herbs — sorrel, parsley, chervil, watercress, sometimes spinach or nettle — cooked briefly in butter with the eel and finished with a little lemon juice or white wine vinegar.

There are no carbs worth counting in it. The eel is rich, fatty, substantial protein. The sauce is butter, herbs, and a small amount of acid. It’s a complete keto meal that requires no modification, no substitution requests, and no explanation.

The eel

Freshwater eel has a distinctive flavour — richer and more pronounced than sea fish, with a firm texture that holds up well to cooking. If you haven’t eaten it before, the flavour is closer to a rich fish like mackerel than to a white fish. Some people find it challenging at first; most come to appreciate it once they stop expecting it to taste like something else.

The eel is cut into sections a few centimetres long, sometimes skinned, sometimes not. It’s cooked briefly — eel doesn’t need long — in the herb butter, which absorbs the flavour of the fish as it cooks. The result is a dish where the butter, the herbs, and the eel have all flavoured each other.

The green sauce

The herb mixture varies by recipe and by season. Sorrel is important — it provides the acidity that balances the richness of the eel. Parsley and chervil are almost always present. Watercress adds a peppery note. Some versions add a small amount of white wine to the sauce, which is fine.

What the sauce isn’t is a cream sauce. There’s no flour, no roux, no thickener. It’s butter and herbs and the cooking juices from the eel, with enough fresh herb volume to give it body and colour. This is why it’s keto without trying to be.

Where to find it in Brussels

Paling in ’t groen is more commonly found in Flemish restaurants than in French-speaking brasseries, reflecting its origins in the Scheldt region. In Brussels, look for restaurants that take Flemish cuisine seriously — there are a few in the older parts of the city near the Grand-Place and in the Flemish-inflected communes like Molenbeek and Laeken. The dish occasionally appears on brasserie menus in Brussels but it’s not as ubiquitous as carbonnade or waterzooi.

The towns along the Scheldt — Dendermonde, Mechelen, Temse — are where you’ll find it most reliably and at its best if you’re ever in that direction. Some of the riverfront restaurants there have been making this dish for generations.

Making it at home

The main challenge is sourcing the eel. Good fishmongers in Brussels carry it — the Marché du Midi reliably has it, and the fish counters at the larger Delhaize stores sometimes stock it. Ask for freshwater eel if you don’t see it displayed. It may need to be ordered.

For two portions:

Melt the butter in a wide pan. Add the eel pieces and cook for two minutes on each side. Add the wine or stock and simmer for three to four minutes. Add the roughly chopped herbs all at once and cook for two more minutes — no longer, or the herbs lose their colour and freshness. Finish with lemon juice and seasoning.

It comes together in under twenty minutes and tastes like something that took much longer. Serve it in deep plates with the sauce pooled around the eel, and nothing else needed.

It’s the kind of dish that makes you wonder why it isn’t better known. The answer is probably that eel is unfamiliar to most people and the name doesn’t help. Their loss.