It’s not really a gratin. And it’s not a Moroccan Tajine but it is spiced like one. Potatoes, tomatoes and peppers are all related and their textures and flavors blend together beautifully here.
Mince 6 cloves of garlic and toss with 1/2 t. ground paprika and cumin, and 1/4 t. cayenne pepper. Finely mince 1 C. fresh herbs (basil, cilantro or parsley or a combination). Add to the garlic along with the juice of 1/2 a lemon, 3 T. red wine vinegar, and 3 T. olive oil. Season with salt.
Thinly slice 1 1/2 lbs. of potatoes and 4 tomatoes into rounds. Slice 3-4 sweet peppers into rings after removing the seeds and core.
Grease the bottom of a 12″ square baking dish or cast iron skillet.
Make 2 layers of potatoes on the bottom of the pan, then drizzle with some of the garlic mixture and sprinkle with salt. Make a layer of tomatoes slices and top with a handful of pepper slices. Drizzle with the herb mixture. Repeat until the pan is full.
To make it a true “gratin”, top it with crumbled feta cheese. Alternately you can add the cheese after it is cooked. Or not at all.
Bake at 375 degrees, uncovered, until it is bubbly and browned on top.