1.
The evening before or a few hours earlier, marinate the butternut squash. Peel the squash and cut the flesh into thin slices. Halve and let soak in a marinade of lemon juice, zest, oil and finely grated garlic. At least 3–4 hours or overnight.
2.
Segment the grapefruits and mix them with the marinade into the squash. Wash and trim the radishes and slice them not too thinly (or simply halve them). Peel the shallots and cut into rings.
3.
Melt the butter in a pan. Sauté the shallots there for a few minutes while stirring. Add the radishes and briefly fry together. Season with salt and pepper.
4.
Lightly salt the char fillets and in a second nonstick pan fry them skin‑side in the remaining oil (2 EL) until crispy. Turn and let cook through over low heat for a few minutes.
5.
Arrange on prepared plates together with grapefruit segments, butternut and radishes and serve garnished with flowers or herbs.