Toss the sweet potatoes with the olive oil, salt and pepper and spread into a single layer on a sheet pan. Roast for 30 minutes until the sweet potatoes are tender and slightly browned at the edges. Set aside and let cool.
In a large bowl, combine the romaine, kale, apples, grapes, pumpkin seeds, feta, parsley and sweet potatoes.
For the vinaigrette, combine the garlic, sherry vinegar, salt and pepper in a small bowl. Whisk in the olive oil until fully combined. Drizzle the vinaigrette in the salad before serving.