Wash the spinach, dry it well, and arrange it on a plate.

Slice the fennel as thinly as possible (a mandoline works best) and place it next to the spinach.

Place the smoked salmon on top of the spinach. Peel the grapefruit segments thoroughly, removing all the white pith, and arrange them on top of the fennel.

Sprinkle some sunflower seeds over everything and serve with a dressing made from olive oil, lemon juice, salt, and pepper.