In a small glass jar or bowl, combine the olive oil, fresh lemon juice, honey, Dijon mustard, salt, and pepper. Shake or whisk vigorously until completely emulsified.
Carefully slice your peaches into thin wedges, cube the avocado, and thinly slice the red onion. Coat the avocado lightly in extra lemon juice to prevent browning.
Spread the baby arugula evenly across a large, wide serving platter rather than a deep bowl to prevent the heavy ingredients from sinking.
Evenly distribute the peach slices, avocado cubes, and red onion over the bed of greens. Sprinkle the crumbled feta cheese and toasted pecans over the top.
Drizzle the emulsified vinaigrette over the salad just before serving. Gently toss with clean hands or wooden spoons to avoid bruising the peaches.
