Bring sweet potatoes to a boil for 10 minutes, drain and set aside.
Cook quail eggs for 5 minutes, remove shells, cut into halve and set aside.
Bring water to a boil, add french beans, let boil over strain and blanch with ice.
Pour lettuce into a mixing bowl, add tomatoes, french beans, black olives, onion, olive oil, stir and set aside.
Pour mayonnaise into a mixing bowl, add mustard, garlic, lemon juice, black pepper, salt, olive oil, whisk together and set aside.
Add cooked sweet potatoes to the lettuce mixture and toss to mix.
Sweet potato salad is ready. Top with quail eggs, mayonnaise dressing and serve.