Season the beef with salt and pepper. Fry briefly over high heat, then remove from the pan and place on a plate. Cover with aluminum foil and let cool or let rest.
In the meantime, prepare the vinaigrette in a large bowl using lime juice, olive oil, chilli, salt, pepper, herbs and agave syrup. Whisk well with a whisk.
First cut the onion into strips and let it steep in the vinaigrette. Then clean the remaining vegetables, dice and add to the vinaigrette.
As soon as the beef has cooled down a bit, cut into narrow strips. Do not throw away the leaked meat juice! Add the meat to the salad and spread the meat juice over the top. Then mix everything well and season again to taste.