Rinse the quinoa in a fine-mesh strainer under cold running water for at least 45 seconds. Shake in the strainer to remove as much water as possible.
Heat 1 tablespoon of the oil in a large skillet. Add the quinoa and cook, stirring, over medium-low heat until the quinoa is light golden brown, about 10 minutes. Add the curry powder and cook, stirring, for 1 minute.
Add 2 cups water and 1 teaspoon salt and bring to a boil.
Cook, covered, over medium-low heat until the water is absorbed and the quinoa is translucent and appears to be uncoiling, 18 to 20 minutes.
Let stand, covered, until cool.
Whisk the remaining 2 tablespoons oil and the lemon juice in a large bowl until blended. Add the cooled quinoa, apple, walnuts, cranberries, and scallions and toss to blend. Taste and correct the seasonings, adding a bit more lemon juice, oil, and/or salt, if needed.
Serve at room temperature.