Butter lettuce with candied walnuts, oranges, and feta

3 cup walnut pieces
6 tablespoons water
6 tablespoons sugar

1 1/4 cup white wine vinegar
5 teaspoon grated orange peel
1 1/4 teaspoon dry mustard powder
2 cups olive oil

4 large heads Bibb, boston, or butter lettuce, leaves torn
15 ounces feta cheese
8 oranges

Preheat oven to 325°F. Scatter nuts on rimmed baking sheet. Add 2 
tablespoons water and sugar; toss until sugar dissolves and syrup coats 
nuts. Roast until water evaporates and nuts are crisp, stirring once, about 
15 minutes. Cool on sheet.

Whisk vinegar, orange peel, and mustard in small bowl to blend. Gradually 
whisk olive oil. Season dressing with salt and pepper.

Combine lettuce and cheese in large bowl. Cut peel and pith off oranges. Cut 
between membranes, releasing orange segments. Add segments and walnuts to 
salad. Toss with enough dressing to coat. Serve, passing remaining dressing.