Place the egg in a small saucepan and cover with cold water; bring to a rolling boil, then turn off the heat, cover, and let sit for 9 minutes.
Peel the egg under cool running water and slice it into halves.
In a small glass jar or bowl, whisk the extra virgin olive oil, lemon juice, Dijon mustard, sea salt, and black pepper until the dressing is thick and creamy.
In a large serving bowl, layer the mixed greens, diced cucumber, halved cherry tomatoes, and rinsed chickpeas.
Flake the albacore tuna directly over the vegetables, incorporating the natural juices from the can for added omega-3s and moisture.
Top the salad with the hard-boiled egg halves and the sliced avocado.
Drizzle the lemon-Dijon vinaigrette over the top and finish with a sprinkle of hemp seeds for a nutty boost.