use grapeseed oil for best results....it has least flavor and itll pick up whatever herb you use.
i like trotter style oils.
so blanch herbs (adding some spinach adds color without a spinach flavor) to get out all that beautiful chlorophyll and cuisinart/blender with oil.
press through cheesecloth. save for up to 2 weeks? i dont know how long it holds, cause once i have it, i love to garnish plates with the neon green stuff