Tender fresh string beans sprinkled with fresh basil leaves and ricotta salata and coated with a homemade mustard vinaigrette. Feta cheese can be substituted if ricotta salata is not available.
Cook beans in boiling water with 1 1/2 tsp salt, about 4 minutes, until just tender; drain and immerse in an ice bath; drain, pat dry and place in bowl with cheese and basil leaves.
Whisk mustard, vinegar, oil, remaining 1/8 tsp salt, and pepper until oil is emulsified; pour over beans and toss to coat.