Superior Falafel Sandwich

Ingredients:
2 cups dry chickpeas (soak them)
1 white onion
3 cloves of garlic
1 Tbsp coriander
1 Tbsp cumin powder
2 tsp turmeric
1 bunch of cilantro
1 Tbsp baking powder
1-3 Tbsp corn starch
1 Tbsp water
1 Tbsp salt
Optional: chili powder

Tahini sauce:
2 cups yogurt
1 cup sesame paste
1 lemon
1 clove garlic
Salt to taste

Topping ideas:

Pickled turnips, pickles, shatta (pepper paste), parsley, tomatoes, cucumbers, sumac, lemon slices