We highly recommend using capers and the caper brine if you can. But, in a pinch, you could try using finely chopped green olives and the olive brine instead! Or, just skip it. If you choose to skip the capers, give the salad a taste at the end. It'll likely be delicious as is! But if needed, add a bit more lemon juice and/or salt to compensate for the tangy, savory flavor that capers have.