Mediterranean Tuna and Radish Salad

    2 tablespoons lemon juice
    3 tablespoons extra-virgin olive oil
    1/4 teaspoon salt, or to taste
    1 pound radishes, thinly sliced
    2 tablespoons chopped fresh parsley leaves
    3 scallions, white and green parts, chopped
    6 large black olives, pitted and coarsely chopped
    2 (6 oz.) cans tuna, drained and coarsely mashed with a fork
    1 medium head romaine lettuce, washed, dried, and torn into
      bite-size pieces

Whisk together the lemon juice, olive oil, and salt in a small bowl.
Combine the radishes, parsley, scallions, olives, and tuna in a
medium-size bowl. Pour the dressing over the salad and toss to coat.
Divide the lettuce leaves among 4 plates. Top with the tuna salad.
Serve immediately.