I'm not usually a victim of good advertising. But in November for the last few years there have appeared posters all over the metro system showing mâche, or lamb's lettuce, in creative enticing images. A teddy bear made of dark green leaves, clutched in the hands of a sleeping child. A dark green leafy football being kicked across a grey field. The advertisements do a good job of contrasting the vibrant green of the lettuce with somber tones. And so when the weather is grey and cold, the lamb's lettuce suddenly seems very appealing: full of vitamins and color and flavor.

There are a lot of nice things about lamb's lettuce. In Paris, it's cheap and sold everywhere. Just looking at it you know it's full of great vitamins and one of the articles I saw mentioned omega oils - another plus. And it's very tasty. It doesn't have the bitterness of rocket. Instead, it has a kind of buttery softness. It would be overwhelmed by too much raw garlic, but it shines with a sharp vinaigrette. It serves as a perfect backdrop for interesting salad elements.

My first thought was to make a kind of eggs-and-bacon salad. Lardons fried to a crispness with a poached egg and the the juices from the bacon serving as a basis for a nice sharp vinegar sauce.

It's also nice with smoked salmon and a crème fraîche and tarragon sauce.

And with magret de canard.

And with blue cheese.

A quick scan in the refrigerator showed I didn't have any of these ingredients. However, the leftover beef from my roast the night before was waiting for inspiration. I love cold roast beef. I almost like it better the next day than on the night I make it. Although warm food usually has more flavor than cold, I find that the opposite is true for beef for some reason. Or maybe I'm just more generous with the seasoning when it's cold?

In any case, it seemed like a providential match.

And it was. I cut the beef in thin strips and sprinkled it over the lamb's lettuce. Then I took about 75 grams of fromage des pyrénées and cut it in matchsticks and added them to the salad. I would have added some plump cherry tomatoes if I had any, but I didn't. And for the sauce I mixed a heaping teaspoon of Dijon mustard with about a tablespoon red wine vinegar, a tablespoon of frozen chopped tarragon and a glug of olive oil. It was sharp and complemented both the beef and the mild cheese perfectly. And underneath it all was the tasty lamb's lettuce, a perfect backdrop.

It was so good I went back and finished the last of the beef and the last of the salad on a second plate.

(Note: if you don't happen to have any fromage des pyrénées in your refrigerator you could substitute a cream havarti or some other mild, creamy white cheese.)