Roast the vegetables: Preheat the oven to 425°F. Toss the sweet potato or squash and mushrooms with olive oil, salt, and pepper. Spread on a baking sheet and roast for 20–25 minutes, tossing halfway, until golden and tender.
Cook the steak: Heat a cast-iron skillet over high heat. Rub the steak with 1½ teaspoons salt, ½ teaspoon pepper, and Aleppo pepper. Add oil to the skillet until just smoking. Sear the steak for 4–5 minutes per side, until it reaches desired doneness. Rest for 10 minutes, then slice against the grain.
Make the croutons: In the same skillet over medium-high heat, drizzle the torn bread with olive oil and season with salt. Toast, stirring occasionally, until golden and crisp, about 5 minutes.
Prepare the kale: Place the kale in a large bowl. Massage with a drizzle of olive oil and a pinch of salt for 1–2 minutes until slightly softened.
Make the vinaigrette: Whisk together the red wine vinegar, Calabrian chiles, garlic, and olive oil. Season with salt and pepper.
Assemble the salad: Toss the kale with half of the vinaigrette. Add roasted vegetables, apple slices, and croutons. Top with sliced steak, Parmesan, and pomegranate seeds. Drizzle with remaining vinaigrette and sprinkle with flaky salt.