I adapted this recipe from Titli Nihan, a very funny British cook on youtube. Always use EAGLE brand sweetened condensed milk. It is slightly offwhite and creamy instead of grey and sticky. For the grated lime peel, you can get small hand graters or "zesters." or simply use a fine cheese grater, but this must be done by hand by holding and rolling the lime around. I suppose you can peel the lime and use a food processor but then you have no garnish. Do not substitute lime for key lime. You can get Nellie and Joe's just about anywhere they sell RealLemon.