Cut the mackerel into bite-sized pieces. Sprinkle with salt and let sit for 5-10 minutes. Pat dry with kitchen paper.

Mix curry powder and flour in a bowl. Coat the mackerel pieces evenly.

Cut king oyster mushrooms into bite-sized pieces. Trim the root of shimeji mushrooms and separate them. Slice garlic thinly and remove the core.

Heat 1 tbsp olive oil in a pan over medium heat. Add mushrooms and sauté until tender. Season with salt and pepper, then remove from the pan.

In the same pan, add the remaining olive oil and garlic. Cook over low heat until golden brown, then remove garlic.

In the same pan, place mackerel skin-side down. Cook over medium-low heat until both sides are thoroughly cooked.