01 - Using a sharp knife, slice off the tops and bottoms of each orange and grapefruit. Following the curve of the fruit, cut away the peel and all white pith. Cut the fruit into rounds or segment into supremes, then set aside.
02 - Halve the avocado, remove the pit, and carefully slice the flesh into thin wedges.
03 - Peel the red onion and slice it into thin, even rings or half-moons.
04 - In a small bowl, whisk together the extra-virgin olive oil, fresh lemon juice, honey or maple syrup, and Dijon mustard until emulsified. Season with sea salt and freshly ground black pepper to taste.
05 - Spread the mixed greens across a large serving platter. Layer the prepared citrus segments, avocado slices, and red onion evenly over the greens.
06 - Scatter the pomegranate seeds and crumbled feta cheese generously over the arranged salad.
07 - Drizzle the whisked dressing evenly over the entire platter. If desired, finish with torn fresh mint leaves and chopped toasted pistachios or walnuts. Serve immediately.