Preheat the oven to 425 degrees Fahrenheit. Line a large, rimmed baking sheet with parchment paper.

Transfer the diced sweet potatoes to the baking sheet and toss with 2 tablespoons olive oil. Sprinkle with salt and pepper and arrange in a single layer. Bake for 10 minutes, then toss and bake for an additional 10 to 15 minutes, until tender and browning. Set aside to cool.

In a medium saucepan, combine the rinsed quinoa and vegetable broth. Bring to a boil over medium-high heat, then reduce to maintain a simmer, cover, and cook until the quinoa has absorbed all the liquid, about 20 minutes. Fluff with a fork and set aside to cool.

To make the vinaigrette, combine all dressing ingredients in a blender or food processor and process until mostly smooth, with small pieces of herbs still visible.

Transfer the chopped kale to a large serving bowl. Sprinkle with a dash of salt and massage the kale until it darkens in color and becomes fragrant, about 15 seconds.

Add the sweet potatoes, quinoa, sunflower seeds, and sliced basil to the bowl. Drizzle with about ⅓ cup dressing and gently toss until coated. Adjust dressing to taste.

Serve the salad at room temperature or cold. Leftovers keep in the refrigerator, covered, for up to 2 days.