hi there. this is an intersting recipe, as traditional gremolata contains no more than parsley, lemon peel, and a little garlic. sometimes, either mint leaves or olive oil is added, but that's about it. i would say that a bunch of parsley is probably equal to around 1 cup once you pull the main parts of the stems off. i've never really seen a bunch any bigger than that. frankly, i don't think that amount of parsley is that important, whether its a cup or a cup and a half. this recipe doesn't mention the food processor, and when i make gremolata with my knife and cutting board, i spare myself the frustration by microplaning the lemon. (and, technically, the term zest refers to the use of a grater to remove the citrus rind.) lastly: mushy horseradish, most definitely. enjoy! -honorspianist