Juice the lemons first and then cut up the rinds, discard the seeds and membranes. Peel the apples, remove the cores, and cut into small chunks. Peel and cut the onions into small chunks. Wash and squeeze dry the currants and raisins. Mix everything together and grind.
Place the ground fruit in a heavy-bottomed saucepan and add the vinegar, water, garlic, ginge