First, partly cook the green lentils over medium-high heat in boiling water to the point where they are just tender enough without being hard. Specific cook time varies from lentil to lentil, so just keep testing them until they begin to turn slightly soft yet still firm. You just don't want mush.
Next, add 1 ½ cups cooked lentils, garlic, parsley, cumin and salt to a food processor and pulse, just until everything is incorporated.
Then, transfer that to a mixing bowl and add the red onion, chickpea flour, baking powder, and chili powder. Mix well, then form the dough into compact, decent-sized patties that are more flat than thick.
Fry in a skillet with olive oil over medium heat for 2-3 minutes on each side, until crispy and golden brown. Place on a paper towel. Cover with foil to keep warm or store in a warming drawer. Serve over a salad or just on their own with dill-tahini sauce.
To make the dill-tahini sauce:
Add all the ingredients together and whisk. Add more water or tahini to get a thinner or thicker consistency, depending on your preference.