In a large bowl, combine lentils, onions, eggs, herbs, and spices. In a small bowl, stir together flour, baking powder, and salt. Stir flour mixture into the lentil mixture just to moisten. Add grated zucchini and stir gently until just incorporated.
In a large skillet, over medium-high heat, warm about ½ inch (1 cm) of canola oil. Drop batter using a large ice cream scoop into hot oil, spreading out a little to make them round. You can fry 3 fritters at once. Fry on each side for about 3 minutes, until golden. Remove to a paper towel lined platter and continue cooking fritters until all batter is gone.
Serve warm, sprinkled with coarse sea salt and topped with dill sour cream.