In a dry skillet over medium heat, toast the pecan halves for about 5-7 minutes, stirring frequently, until they are golden and fragrant. Remove from heat and set aside to cool.
Prepare the Vinaigrette:
In a small bowl or jar, whisk together the olive oil, apple cider vinegar, honey, Dijon mustard, salt, and pepper. Adjust the seasoning to taste if needed. Set aside.
Assemble the Salad:
In a large bowl, combine the mixed greens, sliced apples, crumbled feta, and thinly sliced red onion (if using).
Drizzle the vinaigrette over the salad and toss gently to coat all the ingredients.
Top and Serve:
Sprinkle the toasted pecans over the salad just before serving to keep them crunchy.
