01 - Using a sharp knife, slice off the top and bottom of each orange and grapefruit. Following the curve of the fruit, remove all peel and white pith. Cut the citrus into thin rounds or supreme into individual segments, collecting any juices for the dressing.
02 - Halve the avocado lengthwise, remove the pit, and peel away the skin. Slice the flesh into thin, even wedges and set aside.
03 - Peel the red onion and cut it into paper-thin slices or half-moons. Soak in ice water for 5 minutes if a milder flavor is desired, then drain.
04 - In a small bowl, combine the extra-virgin olive oil, fresh lemon juice, honey or maple syrup, and Dijon mustard. Whisk vigorously until fully emulsified. Season with sea salt and freshly cracked black pepper to taste.
05 - Spread the mixed baby greens across a large serving platter, creating an even bed. Arrange the citrus rounds and segments over the greens in an overlapping pattern. Tuck the avocado slices and red onion throughout.
06 - Scatter the pomegranate arils and crumbled feta cheese evenly over the assembled salad.
07 - Drizzle the prepared dressing evenly over the entire platter. Garnish with torn fresh mint leaves and chopped toasted pistachios or walnuts if desired. Serve immediately.