Curried Shrimp and Sweet Potato Stir-Fry

In a large wok, cover the sweet potatoes with water until submerged. Bring to a boil over high heat and simmer until barely tender, 5 minutes. Drain, reserving 1/4 cup cooking liquid, and set aside.

Pat the wok dry and heat the oil. Stir-fry the onion and scallions until beginning to brown, 4 minutes. Add the ginger, garlic and curry paste. Cook 1 minute more. Stir in the shrimp and stir-fry until pink and curled, 3 minutes. Add the sweet potatoes, reserved liquid, lime juice and 1/2 teaspoon salt. Cook until the sauce has reduced slightly and the sweet potatoes are fork-tender, 3 minutes. Garnish with the peanuts and herbs.