In a small bowl, mix ingredients for sauce (sour cream, lemon juice and lemon zest). Let sit in refrigerator.
In a mini chopper or mixer, blitz the chickpeas with the sesame seeds, lemon juice and garlic. Some chickpea texture is nice, but you can make it smoother if you want to. With a rubber spatula, spoon mixutre into a medium bowl and add tuna, egg, carrot, celery salt, paprika and pepper. Mix well.
Preheat a large nonstick frying pan to medium heat and add olive oil. Make 6 equal patties from tuna mixure. Place in the pan and flatten slightly with a spatula. Let cook for 2-4 minutes on each side, until cooked through.
Immediately serve each cake with a dollop of the lemon cream and sprinkle with parsley or cilantro.