Preheat oven to 425°F (220°C) and line a baking sheet with parchment.
Toss sweet potato cubes with 1 tablespoon olive oil, salt, and pepper.
Spread into a single layer and roast for 20–25 minutes, turning halfway through.
Let the roasted sweet potato cool for 10–15 minutes.
Finely chop the kale and massage briefly with a tiny drizzle of olive oil.
Chop the romaine and add it to a large salad bowl with the kale.
Core and chop the apple.
Thinly slice the red onion.
Whisk apple cider vinegar, maple syrup, Dijon mustard, garlic, salt, and pepper together.
Slowly whisk in the olive oil until lightly emulsified.
Add apple, cooled sweet potato, cranberries, pumpkin seeds, feta, and red onion to the greens.
Drizzle approximately half the vinaigrette over the salad.
Toss gently.
Add additional dressing as needed.
Serve immediately.