Mackerel in Tomato Sauce with Vegetables in Jars

Prepare mackerel (2000 g): if needed, clean the fish, briefly boil it in lightly salted water, cool it, and carefully separate the flesh from the bones. Scald tomatoes (3000 g), peel them, and chop them. Slice onion (1000 g), grate part of carrot (1000 g) and cut the rest into batons, and cut bell pepper (1000 g) into strips.

Place tomatoes (3000 g), onion (1000 g), carrot (1000 g), bell pepper (1000 g), tomato juice (500 g), sunflower oil (250 g), erythritol (200 g), and table salt (50 g) into a large pot. Bring to a boil and cook for 40 minutes until the vegetables soften and the sauce thickens.

Add black pepper (4 g), allspice (4 g), and bay leaf (3 g), then gently fold in the prepared mackerel (2000 g). Cook for another 40 minutes over low heat so the fish absorbs the tomato base without breaking down into paste. At the end, add citric acid (5 g), simmer for 2-3 more minutes, and remove from the heat.

Spoon the hot mackerel in tomato sauce into sterilized jars, seal the lids tightly at once, and cool under a towel. Store in a cool dark place. For a stricter keto approach, keep the portions modest, because a noticeable share of the carbohydrates here comes from the tomato and vegetable base rather than from the fish itself.