Step 1

Place couscous into a large heatproof bowl. Pour stock and water into a saucepan over high heat. Bring to the boil. Pour over couscous. Cover tightly with foil. Stand for 5 minutes. Stir with a fork to separate grains. Set aside to cool slightly.

Step 2

Place beans into a heatproof bowl. Cover with boiling water. Stand for 3 minutes. Drain. Rinse under cold running water to refresh. Pat dry with paper towels.

Step 3

Add beans, tomatoes, parsley, chives, lemon rind, lemon juice, and pepper to couscous. Toss gently to combine. Spoon couscous mixture into serving bowls. Top with tuna. Serve.