Heat oven to 350° F. Spread the pecans on a rimmed baking sheet and toast, tossing once, until fragrant, 6 to 8 minutes. Let cool, then roughly chop.
Squeeze the juice from 1 orange. Peel and cut the other 2 oranges into segments.
Whisk together the vinegar, olive oil, 2 tablespoons of the orange juice, ½ teaspoon salt, and ¼ teaspoon pepper. Add the lettuce, frisée, orange segments, and pecans and toss to combine. Serve immediately.