Roasted Japanese yams with chestnut curry sauce

2. Transfer the sweet potato slices to a shallow bowl. Sprinkle with oil and turn the slices to coat them. Set the potatoes on a nonstick sheet pan in a single layer. Roast them for 20 minutes or until they are just tender when pierced with a skewer.

3. Remove the potatoes from the baking sheet with a wide metal spatula and transfer to a serving platter.

SAUCE

5 tablespoons unsalted butter1 onion, finely chopped1 clove garlic, finely chopped11-inch piece fresh ginger, peeled and chopped1 small carrot, finely chopped2 1/2 tablespoons Japanese curry powder2 1/2 cups chicken stock 1/2 small russet potato, cut into 1/4-inch dice 1/2 small ripe mango, cut into 1/2-inch dice6 canned chestnuts3 tablespoons chestnut liquid (from the can)Salt, to taste1 1/2 tablespoons sugar2 bulbs fresh myoga, very thinly sliced (for garnish)4 leaves fresh shiso, very thinly sliced (for garnish)
1. In a saucepan, melt the butter. Add the onion, garlic, ginger, and carrot. Cook on medium-low heat, stirring often, for 3 to 4 minutes or until slightly softened. Do not let the mixture brown.

2. Add the curry powder and continue cooking on low heat, stirring constantly, for 1 minute. Stir in the stock. Add the potato, mango, chestnuts, chestnut liquid, salt, and sugar. Bring to a boil, lower the heat, and simmer for 7 to 8 minutes or until the potatoes and carrots soften. Remove the pan from the heat. Set aside for 30 minutes.

3. In a blender, puree the curry mixture until smooth. Transfer to a clean saucepan and reheat before serving. Spoon the curry sauce over the sweet potatoes. Garnish with myoga and shiso. - Adapted from Tim Cushman of o ya