Wash the vegetables.
Add a grill pan to the stove to preheat it over medium heat.
Wash the mushrooms thoroughly and dry with paper kitchen towels, then cut in slices/ quarters, whatever shape you like.
Add the butter to a medium pan over medium heat, then add the mushrooms. Season with salt and pepper, then cook on high heat so that the mushrooms are fried and not boiled. Cook until the mushrooms are cooked through, but still crunchy. Add extra seasoning at the end if necessary.
In the meantime, season the meat with salt and pepper to taste, then grill on each side until you can easily turn it without the meat sticking to the pan (time may vary depending on the pan, the stove and how thick the meat is, but this is how you usually know that it is done).
Prepare a salad from the thinly sliced radishes and cucumber, thinly cut red cabbage and the arugola leaves. Season with salt and lemon juice to taste.
Assemble the meat, mushrooms and salad together on a serving plate and enjoy while warm.