For the dip: In a small bowl, stir together the lemon juice and garlic and let sit for 2-3 minutes (this takes a bit of the edge off the raw garlic). Transfer to a food processor, add the parsley and tahini, and pulse until the mixture has the consistency of a thick paste. With the motor running, add the olive oil in a slow, steady stream. Add 2 tablespoons of water and blend until completely smooth. Season to taste with salt and pepper. Place vegetables on plate, service with Tahini Dip.