Wash the apricots, drain, cut in half and remove the stone. Mix 3 tablespoons lemon juice and 25 g sugar with the apricots and marinate for about 30 minutes. Put the apricots into 4 greased ovenproof baking trays. Place the eggs, 75 g sugar, grape juice, grappa, cornstarch, 2 tablespoons lemon juice and lemon zest in a tall narrow pan and mix.
Whisk on the stove at medium heat with the whisks of the hand mixer until thick and frothy (rises in the pot and becomes thick). Spread the zabaglione immediately over the apricots and bake in a preheated oven (electric range: 225 °C/ convection oven: 200 °C/ gas: level 4) for 8-10 minutes (or briefly under the grill). Dust with icing sugar and serve immediately. Decorate with balm leaves if desired