1. Bring a large pot of salted water to a boil, plunge in the green beans and cook for about 5 minutes. Once perfectly cooked, drain in a colander.

2. To make the marinade, mix the chopped shallot or onion in a bowl with the herbs, mustard, vinegar, and 4 tablespoons of extra virgin olive oil. Season with salt and pepper to taste, then add the cooked green beans and mix well. Set aside to allow the green beans to cool and absorb all the delicious flavors.

3. Place the beef fillet on a cutting board and season with salt and pepper. Pass the thyme sprigs under hot water for a few seconds to help release their fragrant oils. Remove the leaves from the stems and chop them coarsely. Sprinkle the thyme over the beef fillet, then roll the meat on the cutting board so that any excess seasoning and herbs stick to it.

4. Heat a heavy skillet and add a drizzle of oil, followed by the beef fillet. Sear for 1 minute only, turning every few seconds to sear and encrust all the flavors on the surface. Remove the meat from the skillet and place it on a plate to rest for a minute. (Once ready, serve immediately or store the meat in a covered dish until use. It is preferable not to store it in the refrigerator.)

5. Using a sharp knife, slice the seared beef fillet into thin slices. Place each slice on a cutting board and flatten it as much as possible by pressing down on it with the side of a knife. Place two or three slices in each plate. Season again lightly, place a pile of green beans on top, and drizzle with a little marinade. Sprinkle the remaining herb leaves and drizzle with extra virgin olive oil.