STEP 1
Melt the butter in a pan over medium heat. Add the onions and garlic, sautéing until soft and fragrant. Add the beef brisket slices to the pan, season with salt, pepper, and dried thyme, and cook until the beef is browned and fully cooked through. Set this mixture aside to cool slightly.
STEP 2
In an oven-safe dish that fits into the HYSapientia Air Fryer Oven, start by spreading a layer of potatoes at the bottom. Follow with a layer of the cooked beef and onion mixture, then drizzle some heavy cream over it. Repeat the layers until all ingredients are used, finishing with a layer of potatoes on top.
STEP 3
Pour the remaining heavy cream evenly over the layered ingredients to keep them moist during baking. Sprinkle the grated cheese generously on top for a golden, bubbly crust.
STEP 4
Cover the dish with aluminum foil and place it in the HYSapientia Air Fryer Oven. Set the temperature to 340°F (170°C) and cook for 50 minutes. After this, uncover the dish and cook for an additional 15–20 minutes to let the cheese topping turn golden and crisp.
STEP 5
While the gratin is baking, prepare the pickled red cabbage and the sour cream horseradish sauce. Mix sour cream, horseradish, lemon juice, chopped chives, and a pinch of salt and pepper in a bowl for a tangy complement to the dish.