I use a very similar recipe. The devil is in the detail (proportions of lemon, garlic, tahini, water, etc). I make it by taste rather than by quantities from recipe as it depends on the ripeness and juiciness of the lemons. I also prefer a less thick texture, which is achieved by adding water and blending until the desired consistency is achieved. Like @scubadoo97, I add freshly roasted and ground cumin to taste.
Try adding a small pinch of cayenne pepper, which is not enough to make it hot but plenty enough to make it interesting.