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 white pith. Cut the citrus into rounds or supreme into segments, collecting any juices.
02 - Halve the avocado, remove the pit, and peel away the skin. Slice the flesh thinly and set aside.
03 - Peel the red onion and cut it into thin, even slices.
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. Arrange the citrus segments, avocado slices, and red onion evenly over the greens.
06 - Scatter the pomegranate seeds and crumbled feta generously over the assembled salad.
07 - Drizzle the dressing evenly over the entire platter. If desired, finish with torn fresh mint leaves and chopped toasted pistachios or walnuts. Serve immediately.