Carefully remove the tuna from the can, leaving the loin pieces intact. Reserve the olive oil. Place the tuna in the refrigerator while you prepare the remaining ingredients.
Divide the lettuce between 2 plates and carefully lay the tuna atop the leaves. Top with the shallot, bell pepper, capers, hard-boiled egg and micro greens. Sprinkle with black lava sea salt. Drizzle the salad with the reserved olive oil and a squeeze of lemon.