Put 2 each cubed Yukon gold potatoes and sweet potatoes in a pot of cold salted water; bring to a boil and cook until tender, 5 to 8 minutes. Drain and pat dry. Heat 2 tablespoons vegetable oil in a large skillet over medium-high heat. Add the potatoes and cook, turning, until browned, 8 minutes. Stir in 1 teaspoon grated ginger, 1/2 teaspoon grated garlic, 1 teaspoon curry powder, and salt and pepper to taste; cook 1 minute. Sprinkle with chopped cilantro.