oh dear...oh dear...oh dear........
gremolata is a mixture of lemon rind, garlic, herbs such as rosemary, parsley etc. in Italy they sprinkle it on ossobuco.
try the recipe here:
http://www.italianmade.com/recipes/recipe317.cfm
and here's some background on pesto and how it's made:
http://www.italianmade.com/recipes/recipe86.cfm