Preheat the oven to 450°F. Line a baking sheet with parchment paper.
Cut the sweet potatoes into a matchstick shape. Place them in a large bowl and toss with the nutritional yeast, parsley, garlic powder salt, hot pepper flakes, and lemon juice.
Place on the prepared pan and bake for 30-40 minutes, until the potatoes are soft and slightly browned.
Meanwhile, soak the walnuts in boiling water for at least 30 minutes.
Drain the walnuts and add to a food processor along with the garlic and turmeric. Blend and slowly add in the milk until you achieve a thick aioli sauce. Season with salt to taste.
When the sweet potatoes are cooked, cool slightly then serve with the aioli. Enjoy!