Place raw quinoa in a fi ne mesh strainer and rinse under cool running water. Place rinsed quinoa in a saucepot with 1½ cups cold water. Place on medium heat and bring to a simmer. Cook until quinoa becomes translucent on sides and is tender, about 10 minutes. If necessary, add additional water while cooking. Drain quinoa in fine mesh strainer. Rinse under cool water.
In a mixing bowl, combine vinegar, mustard, maple syrup, salt and pepper. Whisk to combine. Slowly whisk in 1/3 cup extra-virgin olive oil.
Tear cleaned escarole leaves into large bite-sized pieces and place in mixing bowl. Heat remaining 1 tablespoon olive oil in grill pan or large skillet. When hot, add escarole leaves. Turn heat down to medium. Sauté for one minute, using metal tongs to turn leaves to evenly cook. If needed, do in batches. The escarole will be just warm with some of the tips of the leaves slightly charred.
Place the warm escarole in a large mixing bowl. Add the sliced apples, radish, cooked quinoa and walnuts.
Drizzle with enough dressing to just coat and gently toss.