Boil or steam sweet potatoes until fork tender. Add into your food processor, drizzle with truffle or olive oil, add a pinch of unrefined salt and process until silky smooth, scraping down sides as needed. Reserve.
While potatoes are cooking, add olive oil in a large skillet over medium heat and put sliced portobello mushrooms. Sprinkle with salt and pepper. Cook until dark in color and caramelized, about 5-6 minutes. You want to cook them on both sides at high heat but without smoking the oil.
Trim asparagus, add them in a separate skillet drizzled with olive oil, sprinkle asparagus with salt and pepper, and cook on medium heat until tender, about 5-6 minutes. (You can cook them at the same time of the mushrooms in a separate skillet.)
Make the sauce by combining all ingredients into a food processor and process a few times to make the sauce. Transfer to a glass jar and reserve. Refrigerate leftover sauce.
Arrange plates by putting mashed potatoes first, then arrange portobello "steak" strips on top, add asparagus and drizzle sauce on top of mushrooms.