Your capers substitute is ready to use. GREEN OLIVES. Green olives can be used as a substitute for capers in recipes. But since they are much bigger than capers, it is better to take only half the number of olives while using it as a substitute. So for every four capers that you would add, use just two green olives.asturtium is a flower that can be eaten whole along with its leaves. It has a peppery taste that can greatly enhance the flavor of a salad or pasta. Its seeds can be used as a substitute for capers when pickled.