Wash and Wipe dry sweet potatoes. Slice then into 1-2 inch thick slices on a bias.
Line a baking sheet with Silpat or nonstick aluminum foil.
Arrange slices on sheet.
Brush slices with olive oil on both sides.
Season with 1/2 teaspoon salt.
Bake slices for 25 minutes till soft.
Remove from oven and keep warm.
While potatoes cook blend arugula, cilantro, serrano pepper, remaining salt, pepper and olive oil into a thick puree. Scrape into a bowl.
Mix ricotta till smooth.
Start by topping slices with a scant tablespoon of ricotta. Arrange a dollop of arugula puree on top of ricotta and serve as an appetizer or side.