Food & Cooking Recipes Dinner Recipes Dinner Side Dishes Autumn Tian 3.5 (56) 6 Reviews By Martha Stewart Test Kitchen Martha Stewart Test Kitchen The recipes developed by our test kitchen team have undergone a rigorous process of development and testing, ensuring that every element is optimal, from ingredient amounts to method and cooking time. This process includes triple-testing recipes to ensure they meet our high standards. The many stellar cooks and food editors who have been part of our team include Sarah Carey, Lucinda Scala Quinn, Jennifer Aaronson, Shira Bocar, Anna Kovel, Greg Lofts, Riley Wofford, Lauren Tyrell, and Lindsay Leopold. Editorial Guidelines Updated on February 21, 2023 Print Rate It Share Share Tweet Pin Email Photo: Chris Court Prep Time: 30 mins Total Time: 3 hrs Servings: 8 Ingredients 1 pound beets (about 3 medium), preferably a mix of red, golden, and Chioggia, trimmed and scrubbed 1 medium onion, thinly sliced 6 tablespoons extra-virgin olive oil 1 tablespoon fresh thyme leaves Coarse salt and freshly ground pepper 1 pound Yukon Gold potatoes (about 2 medium), peeled and cut into ¼-inch slices 1 pound plum tomatoes (about 3), cut crosswise into ¼-inch slices Directions Preheat oven to 400 degrees. Wrap beets tightly in parchment-lined foil. Roast on a baking sheet until tender, about 1 hour, 20 minutes. Let cool completely. Peel and cut crosswise into 1/4-inch slices. Increase oven temperature to 425 degrees. Toss onion with 1 tablespoon oil and half of thyme. Season with salt and pepper and arrange in the bottom of a 3-quart round or oval gratin dish. On a cutting board, stack 1 slice each potato, beet, and tomato. Season with salt and pepper. Repeat with remaining vegetables, keeping each stack separate. Transfer stacks to dish and shingle to overlap slightly. Sprinkle with remaining thyme and drizzle with 2 tablespoons oil. Cover tightly with parchment-lined foil. Bake 30 minutes. Uncover; drizzle with remaining 3 tablespoons oil. Bake, uncovered, until vegetables are tender and tomatoes are caramelized, about 35 minutes more. Let cool slightly before serving. Rate it Print