You can do all the slicing and chopping a day or two before, then assemble and add the lemon, salt, black pepper and olive oil about an hour before you’re ready to serve so the flavours can meld together. The finished tabbouli can be stored in an air-tight container in the fridge for up to three days. Unfortunately, you cannot freeze this tabbouli as some of the ingredients, like the tomatoes and cucumber, have high moisture content and will become mushy after freezing.