Prepare the grapefruit: Peel the grapefruit and cut it into segments by slicing away the membrane between the segments with a sharp knife. Alternatively, you can use a serrated knife to carefully cut away the skin and pith, then slice the fruit into rounds or wedges.

1. Prepare the avocado: Cut the avocado in half, remove the pit, and carefully scoop out the flesh. Slice the avocado into thin wedges.
2. Assemble the salad: In a large bowl, combine the fresh spinach, grapefruit segments, and avocado slices. If using, add the thinly sliced red onion and chopped walnuts for extra texture and flavor.
3. Make the dressing: In a small bowl, whisk together the olive oil, lime juice, honey (or maple syrup), and a pinch of salt and pepper. Taste and adjust the seasoning, adding more lime juice or sweetener as needed.
4. Toss the salad: Drizzle the dressing over the salad and gently toss to combine, making sure all the ingredients are evenly coated.
5. Serve: Serve immediately as a light lunch, side dish, or a refreshing starter for dinner. Enjoy the freshness and vibrant flavors!