Chop peeled tomatoes into cubes, cut peeled onions into 1cm cubes, cut peeled and cored apples into 1cm (½ in) cubes, peel cucumber and cut into cubes taking out the seeds.
Combine tomatoes, onions, cucumbers and apples in large bowl, sprinkle salt over – cover and stand for a few hours overnight.
Combine vinegar and sugar in large pan, stir over heat until sugar dissolves. Bring to boil, add drained vegetables, bring back to boil, reduce heat. Simmer 10 minutes.
Mix flour, curry powder, garlic and turmeric to smooth paste with water, add to pan, stir until mixture boils and thickens. Reduce heat and simmer 10 minutes, or slightly longer to get to the consistency that you like.