The owner of Le Cirque set out to make two pasta dishes for his friends while on vacation, one with vegetables, one Alfredo style. But in the end he mixed the vegetables with spaghetti and cream together, and Spaghetti Alla Primavera soon became a regularly-requested item at the restaurant.
This perfect rendition, from Claudia Roden's masterpiece cookbook The Food of Spain (HarperCollins, 2011), is a deceptively simple mixture of olive oil, white wine vinegar, chopped parsley, and crushed tomato. Somehow it telegraphs coolness and warmth, acidity and richness all at the same time.
The origins of leeks vinaigrette—poached leeks in a mustardy dressing—are unknown, but it's easy to imagine someone pulling them out of the stockpot once they had worked their magic, then seasoning them.