Onion - Don't dice the onion too fine, or else it will water. If you want, you can soak the chopped onion in cold water for 5-10 minutes. This helps make it taste milder.Cucumber - Use English cucumbers or mini cucumbers if available. These have a firm texture, thin skin, and fewer seeds than traditional cucumbers. If using a regular cucumber, then peel and deseed it.Tomato - Use a firm tomato and deseed it if it has too many seeds.