Wash the fruit and peel the mandarin orange. Cut the oranges and one of the lemons – with their peel on – into thick slices, and then cut each slice in half. Put them into a large glass jug with a wide “mouth” (big enough for a serving spoon or, better still, a ladle to pass through it), together with the mandarin segments and the apples, which you have previously cored, cut into segments and then into pieces. Add the sugar and the juice of half a lemon and stir delicately. Leave for about half an hour, then pour the bottle of grape juice into the jug and put it in the fridge to rest for 2 or 3 hours.
When you want to serve the Sangria, add ¾ of a bottle of sparkling wine (or the amount you prefer for the "right" alcohol content) pouring very slowly so as not to create too much froth. Give another quick stir, taking care not to take the “fizz” out of the sangria, add more sugar if necessary and… all that’s left to do is fill the glasses, decorating them with a slice of orange (cut a small slit in one side), and adding a long-handled spoon and a cocktail straw.
Another idea is to prepare an alcohol-free version for children. The method is the same: you need to increase the quantity of grape juice (maybe take the skin off the fruit) and as a final “touch”, to make them feel big, a drop of fizzy water (or even soda water)!