Preheat oven to 450 degrees.
In a medium bowl, whisk chickpea flour, oil, salt and pepper with water until smooth. Set aside.
In a nine-inch cast iron skillet, heat olive oil over medium high heat and add onion, stirring until glossy, about 5-7 minutes. Add fennel and cumin and saute for 3 minutes.
Stir in garlic and tomatoes and saute for 2 minutes. Turn off heat, sprinkle sumac over veggies and stir into chickpea mixture. Immediately place mixture back into skillet, even it out with a tap and a jiggle and place in the oven. Bake for 12 minutes or until the farinata is firm to the touch.
Meanwhile, mix up the dressing: whisk together lemon juice, olive oil and capers in a medium bowl and season to taste. Toss with greens.
Serve farinata topped with herb salad.