1. Peel and finely chop the shallots. Put them in a saucepan, add the vinegar and reduce by half over low heat.
2. Remove from the heat and add the egg yolk, then place the pan in a double boiler.
3. Let the egg take without stopping to stir. As soon as it starts to take on a slightly hard consistency, remove from the heat.
4. Adjust the seasoning, stir in the finely chopped tarragon and let cool. Gradually mix with the cream.
5. In a non-stick skillet or on a hot grill, sear the sirloin steaks 30 sec per side.
6. Season with salt and pepper and serve immediately, accompanied by steamed green beans and light béarnaise sauce.
Tip: You can also add to this light béarnaise, two tablespoons of cooked total coulis and replace the tarragon with mint leaves.