Wash the peppers, carefully cut away the top with the stem at the upper edge, then carefully remove the core inside with your fingers.
Bring the long-grain rice to the boil once in 400 ml of lightly salted water, then cook over a low flame at a very low temperature in a closed saucepan.
When after just under 10 minutes the long-grain rice has swelled and only a little water remains, leave the long-grain rice to swell in the closed cooking pot without adding heat. Allow the long-grain rice to cool.
In a large bowl, mix the minced meat with the finely chopped onions, a pressed clove of garlic, the egg and the spicy mustard very well, preferably with your hands.
Then incorporate as much long-grain rice so that the filling is half long-grain rice and half meat. Let stand for 20 minutes and then season again.
Fill the peppers with the mixture, carefully pressing it into the pods with your hands.
Chop the stem ends from the canned tomatoes and chop the tomatoes.
In a large saucepan, heat olive oil and sauté peppers on all sides until browned and skin is blistered.
Remove the peppers from the saucepan and in the same olive oil, briefly sauté the peeled and halved garlic cloves until golden.
Deglaze with the prepared canned tomatoes (with juice), add a pinch of sugar and the two bay leaves, pour port wine, boil everything together once,