Before you begin, I have a few tips for you. Take care that all your vegetables and herbs are equally finely chopped and your pieces of fish cut to the same size to ensure they marinate evenly. It's important to consider the texture, as well as flavour of the ingredients in your ceviche. (Need to hone your chopping style? Why not sign up to our Knife Skills course.)
Secondly, do keep a stop-watch in hand when marinating seafood. All fish react differently to citrus juices. While octopus can happily steep overnight and shrimps and prawns for up to 4 hours, delicate white-fleshed fish and scallops need no more than 30 to 40 minutes. It's usually wise to steer clear of oily, soft textured and strong tasting fish such as sardines, mackerel and tuna in ceviche.
Finally, and most importantly, use the freshest fish possible.