Put 3 sweet potatoes on a baking sheet and bake at 400˚ until soft, about 1 hour. Peel, then puree in a food processor with 1/3 cup tahini, 1 tablespoon each olive oil and lemon juice and 1 grated garlic clove; season with salt. Thin with water as needed. Transfer to a bowl. Spread 1/2 cup mini marshmallows on a baking sheet and broil until toasted. Top the dip with the marshmallows, pomegranate seeds and toasted sesame seeds. Serve with sweet potato chips.