In a large sauté pan, heat the oil. Add the onion, jalapeño, mushrooms, garlic, and carrots and cook over moderate heat, stirring occasionally, until tender and all of the moisture has evaporated, about 10 minutes. Let cool slightly.
In a large bowl, mash half of the black beans with a fork or potato masher. Add the cooked vegetables, cilantro, scallions, rolled oats, turmeric, and cornstarch. Stir until you have a cohesive mixture. Season with salt and pepper. Cover and refrigerate the mixture for at least 2 hours.
When chilled, form your patties, about 4 to 6 ounces each, and ½-inch to ¾-inches thick. To serve, heat some oil in a nonstick skillet and sear the patties in batches over moderate heat until golden brown and heated through, about 3 minutes per side.
Serve on toasted buns with homemade aioli, roasted tomatoes, dill pickle chips, and cilantro, if desired. Enjoy!