Preheat the oven to 375 degrees. Pierce the sweet potatoes a couple of times with a fork and roast on a small baking sheet until soft, about 50 minutes.
Smash the garlic cloves and sprinkle with a pinch of salt. Using the flat side of a large knife, mash the mixture into a coarse paste. Add to the mayonnaise along with about 2 tablespoons water. Gradually whisk in the olive oil and season with pepper.
Halve each sweet potato lengthwise, sprinkle with salt and pepper and top with the aeoli.
Photograph by Tina Rupp
Recipe courtesy Food Network Magazine