Place the vine leaves in a bowl and pour over boiling water.
Soak for 2-3 minutes, drain in a sieve and rinse under cold water to cool. Pat dry with kitchen paper.
Peel and finely chop the onion.
Mix in a bowl with the herbs, minced meat and rice. Season with salt and pepper.
Separate the eggs. Beat the egg whites until stiff.
Fold the egg whites into the mince mixture.
Remove the stalks from half of the vine leaves.
Place the prepared vine leaves, shiny side down, on the work surface. Place 1-2 teaspoons of the mince filling on each vine leaf just above the stem. Wrap the sides over the filling then roll up from the bottom.
Line a small pot with the remaining vine leaves. Place the filled vine leaves on top. Drizzle with 3 tbsp olive oil and pour in 375ml water. Place a flat dessert dish upside down on the vine leaves and press down firmly. Cook over a low heat for 60 minutes.
In a bowl, beat the egg yolk with the lemon juice, salt and pepper.
Heat the butter and 1 tbsp flour in a pan until foamy. Pour in the stock and simmer, stirring, until creamy. Drain the cooking liquid from the vine leaves into a bowl and add to the sauce. Stir 2-3 tbsp of the hot sauce into the egg and lemon mixture, then mix it back into the sauce. Season with a pinch of sugar and salt.
Pour the sauce over the vine leaves and keep warm.
Cut the feta cheese into 8 slices and season with pepper. Turn in the remaining flour to coat. Heat 2 tbsp olive oil in a frying pan, fry the feta until lightly browned on both sides. Serve with the vine leaves and sauce, garnished with dill.