Begin by washing and drying your fresh baby spinach leaves. Place the cleaned spinach in a large salad bowl, ensuring it's completely dried to avoid sogginess.

Select a ripe mango that's slightly soft to the touch for the best flavor. Slice off the sides to expose the flesh, then carefully dice the flesh into cubes.

Gently fold the blueberries into the bowl with the spinach and mango.

Add thinly sliced red onion and crumbled feta cheese into the mix if desired, stirring gently to ensure even distribution.

In a small bowl, whisk together olive oil, freshly squeezed lemon juice, and honey, if using. Drizzle this dressing over the salad.

Gently toss all the ingredients together using salad tongs or a large fork.

Sprinkle chopped walnuts over the top of the salad for a satisfying crunch.