Beef with yolks

1 1/2 lb beef tenderloin cut thin strips 2 Tbsp. finely-diced or possibly grated white onion 4 Tbsp. butter 2 Tbsp. extra virgin olive oil 1 1/2 c. beef[...]

1 pound of beef tenderloin Canola, grape seed, or olive oil 4 thin slices of ham or prosciut 2 tablespoons of yellow mustard 1 pound of mushrooms (we used[...]