Nicoise Salad with tuna

Name: Nicoise Salad with tuna
Prep time: 5 min
Cook time: 20 min
Total time: 25 min
Cuisine: French, Mediterranean, European
Ingredients: Green beans halved lengthways; 1 boiled potato, chopped; 1 cup butter lettuce, leaves shredded; 3 cherry tomatoes; Tbsp black/green pitted olives, halved; 1 anchovy fillet (marinated in oil and salt only), drained and chopped; 1 can tuna in oil; ½ tsp mustard; Rice wine vinegar; 1 hard-boiled egg, halved