Heat oven to 350 F. Heat oil in a pan over medium heat. Add onion and cook until transparent, 8-9 minutes. Add the garlic and cook just until fragrant, stirring constantly to avoid burning, about 30-60 seconds. Add potato starch to the onions and mix well. Add mayonnaise, water, soup powder, and salt, and cook for 2-3 minutes until thickened, stirring constantly. Set aside. Pour a thin layer of sauce into an 8 X 8 baking dish, covering the bottom. Place a layer of overlapping potato slices in the pan, then sprinkle on some of your asparagus. Top with a layer of sauce. Sprinkle with salt, pepper, and paprika. Repeat twice, for a total of 3 layers of potatoes, asparagus, sauce, and spices. Bake uncovered for 1 hour. Remove from oven, add crushed potato chips, and bake for 30 minutes, or until potatoes and asparagus are fork-tender. Garnish with fresh dill, if desired.