Rachel Roddy’s recipe for potatoes, onions and green beans | A kitchen in Rome

Inspired by her favourite Italian detective Montalbano, our Roman sleuth tracks down the perfect summer dish

As he breaks three eggs into a glass bowl, Lt Columbo tells Joanna Ferris: “I’m the worst cook in the world, but there’s one thing I do terrific, and that’s an omelette.” The episode is Murder By the Book, and Columbo has taken Joanna, the wife of murder victim Jim Ferris, home to save her from more relentless questioning by his colleagues. Of course, we already know it was Jim’s less talented writing partner, naughty Ken Franklin, who did it.

At first, Joanna resists Columbo’s offer of something to eat, but he gently gets on with it, in his trademark raincoat: he cracks the eggs into a bowl, picks out a bit of shell that inadvertently falls into the bowl and asks Joanna where he can get a bowl for the empty shells balanced in his hands. It is a perfect scene and perfect Columbo: bumbling and absolutely certain, attentive to needs and tiny details.