Almost any fish will do for this recipe, but my goal was mackerel. I had a whole fish weighing a little more than half a kilogram. Slightly froze the carcass to make it easier to cut into fillets. If you have a ready-made fillet, it's even easier. The net weight of my fillets is 400g. Wash the fillet (I removed the large bones) and dry it with a paper towel to get rid of excess moisture.
With lemon (or lime, as I have), remove a little zest (you will need about 1/2 tsp), squeeze the juice. We will use the zest in the sauce. Garlic is best ground in a mortar or passed through a press. RUB the fish with salt and pepper mixture, pour lemon juice. RUB the garlic on all sides and cover with mustard. In the original recipe, the chef uses hiomi seasoning. This seasoning, obtained from dried tree bark, has a garlic-mustard taste. This is impossible to find, so I replace it with mustard and garlic. Leave the fish to marinate for 30 minutes or longer.
Cut the onion into feathers. in a frying pan, melt the butter and add the onion. Fry for a couple of minutes over medium heat. Add 2 tablespoons of broth. If you had a whole fish, then while the fillet is marinated, you can prepare a broth from the head and spine. Or use your ready-made broth, I have mushroom.
Put the fish on the onion. Cook for 5-7 minutes, turn over. Another 5-7 minutes. As the liquid evaporates, add a tablespoon of broth to the onion is not burnt.
When we turn the fillet, remove the onion that was left on the fish and put it under it. The idea is that the fish is not fried, but it is not cooked, it is cooked on an onion pillow.
Remove the fillet from the pan, add the zest and remaining broth (it may take a little more or less broth than indicated in the recipe, be guided by the amount of sauce you need). For sure, after marinating the fish, you have a little marinade left in the bowl, add it to the sauce. At this stage, the chef adds a couple of pinches of flour to thicken the sauce. I replace the flour with yogurt, which gives the sauce a delicate texture and fresh taste. The choice is yours. Boil the sauce for a couple of minutes, if necessary, adjust the salt. Return the fish to the pan, turn out the heat, cover and let stand for 10 minutes.
Serve fish chef advises with vegetables, watering it with sauce and onions, but any side dish is perfect.
Garlic is almost invisible. Onion sauce is excellent, soft with a pronounced lemon flavor. In addition, the fish is delicious and cold, you can serve it as a snack or make a riyet.