I don't have a recipe, but I always use the same amount by volume of mint & flat-leaf parsley. My tabouleh is more green than wheat-berry brown when I'm done mixing
For me, the lemon is a must, and while fresh with some zest is great, reconstituted in the bottle works fine too. Edit to note: tabouleh is great for summertime picnics and get-togethers because it won't spoil or make people ill if not refrigerated or kept cool like some mayo-based salads might.