In a small bowl, whisk together the lemon juice, zest, garlic, oil, and parsley and season with salt and pepper. Set aside.
Put the snow peas in boiling water for 2 minutes, and then shock them in cold water to stop them from overcooking.
In a large bowl, put the lettuce, onions, and snow peas and toss with the vinaigrette. Top with the almonds, capers, tuna, and sliced eggs. Serve immediately.