Marinate the foie gras in the sweet wine for six hours in the refrigerator. Trim the fillet and cut it into sections. Cut the sections in the same direction as the grain and beat each slice with a meat pounder. Season with salt, oil and black sesame seeds.
Thinly slice the marinated foie gras over the fillet to substitute the missing fat. Season with little drops of umeboshi (Japanese plum vinegar, available in ethnic food stores) and Béarnaise sauce. Garnish with lettuce leaves.
To prepare the Béarnaise sauce
Julienne a shallot, place it in a small saucepan with the vinegar and cook over a low heat, reducing the vinegar by ¾. Put the egg yokes together with the shallot and vinegar into a stainless steel bowl and place over a bain-marie. Incorporate the clarified butter with a whisk. Season with salt.
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