Rinse prawn, pat dry, (about 4-5 set aside) and chop finely. Peel and dice onion. Puree prawn pieces, onion, mustard, mayonnaise, egg, and lime zest in an electric grinder. Stir breadcrumbs into the mixture. Season with salt and pepper. Rinse chives, shake dry, cut finely (set some aside for aioli) and stir into the mixture. Then refrigerate.