Soak the chickpeas overnight in a large bowl.
Make sure to add enough cold water to cover them by at least 2 inches. In the morning drain the chickpeas.
In a food processor or blender add the drained, uncooked chickpeas and the onions.
Then add the parsley, cilantro, salt, chili pepper, garlic, and cumin.
Process until blended but not pureed.
The mixture should be a fine crumbly texture.
Sprinkle in the baking powder and 4 tablespoons of the flour, and pulse.
You want to add enough flour so that the dough forms a small ball and no longer sticks to your hands.
Empty the falafel mixture into a clean bowl and refrigerate, covered, for several hours.
Form the falafel mixture into balls about the size of walnuts.
I like to flatten mines into a patty which allows for even cooking.
In a frying pan heat oil to 375 degrees in a deep pot and fry 1 ball to test.
If the falafel falls apart, add a little more flour to the mixture.
Then fry the falafels for a few minutes on each side, or until golden brown.
Drain on paper towels. Drizzle with tzatziki sauce.
Add a few slices of lemon to the plate and serve.