There are some really simple tips to follow when you are whipping up a great ceviche.  1. Use fresh ingredients | This should go without saying, but it doesn't always. If you can buy some fresh shrimp from the fishmonger, do it. Source the best vegetables you can, and make this when they are in season. The end result will be much better, and you can really tell a difference.  2. Account for the marinating time | This is important! Not so much for this grilled shrimp ceviche because the shrimp is fully cooked prior to putting the ceviche together, but for other preparations, you need to leave about an hour to allow time for the fish to "cook" in the acid.