1 pound sweet potatoes, peeled
1 can coconut milk, shaken to combine contents
1 tablespoon lime juice
1 teaspoon ground turmeric
2 tablespoons fish sauce
1 cup pecans
2 tablespoons tamarind paste
1/4 cup vegetable oil
1 cup water
2 tablespoons sugar
1 teaspoon coriander powder
1 tablespoon soy sauce
2 finger chilis
4 cloves garlic, peeled
1/2 red onion, diced
1 stalk lemongrass, cut into strips
2 tablespoons galangal or ginger, peeled
1. Heat oven to 425°F (220°C). Cut sweet potatoes into cubes. Whisk coconut milk, lime juice, turmeric, and fish sauce together in a bowl. I didn't mix the coconut milk well enough in the can to combine it, so there were flecks of solid bits in the mixture. Soak potato chunks in the mixture until oven is preheated.
2. Place potato chunks on skewers and brush all surfaces in oil. Bake for 20 minutes, rotating every 5 minutes, or until a toothpick easily pierces the flesh.
3. Use a food processor to grind the pecans into tiny pellets. Set aside.
4. Chop the chilis, garlic, and onion coarsely. Process in a food processor until finely chopped. Add a few tablespoons of water to help blending if needed.
5. Heat the oil in a pan on medium heat. Stir in ingredients from step 2. Heat, scraping the pan occasionally, until the onion and garlic starts to become translucent.
6. Add strips of lemongrass to the pan. Cook the spice paste until it becomes aromatic and smell spicy.
7. Add the ground pecans, water, tamarind paste, sugar, coriander powder and soy sauce. Stir to combine well.
8. Turn the heat to medium-low, stirring continuously for about 5-10 minutes or until the peanut sauce thickens to your desired consistency.
9. Let cool at room temperature and serve the sauce with potato skewers.