Heat a stockpot over medium heat for 2 minutes. Add the onion and garlic and saute for 5 minutes, adding a splash of water when they stick to the bottom.
Stir in the peas, broth, dill, salt and pepper. Bring to a boil over high heat, then reduce the heat to medium-low and place a lid on the pot at an angle. Simmer for 10 minutes.
Turn off the heat and allow to cool for 10 minutes.
Transfer the Soup to your blender and add the tahini. Blend until perfectly smooth.
Transfer the Soup back to the pot, add the lemon juice and parsley, then stir.