Preheat the oven to 180°C (160°C fan, gas 4). Score the skin side of the meat several times in a criss cross pattern.
Season the meat with salt and pepper.
Roast in a roasting tin, skin side down, until golden brown. Baste several times with the juices. Remove from the tin.
Peel and dice the onions. Wash the carrots and celery and cut into 1.5cm cubes.
Lightly fry the vegetables in the meat tin, turning regularly. Halve the garlic bulb diagonally and add to the tin with the herbs.
Brush the flesh of the pork with mustard and place, skin side up, on top of the vegetables.
Pour the beer around the sides and cook in the preheated oven for 45-50 minutes.
Set the meat aside to rest. Strain the vegetables in a sieve, reserving the juices. Season the cooking juices with salt and pepper.
While the meat is roasting, prepare the coleslaw. Remove the outer leaves, wash the cabbage, cut into quarters and remove the stem in a wedge shape. Cut the leaves into fine strips with a knife (or mandolin). Peel and finely chop the onion. Cut the bacon into thin strips. Fry the bacon in a pan until golden brown, add the onions and cabbage and sauté briefly.
Add the cumin, pour in the vinegar and stock, then bring to the boil. Remove from the heat and allow to cool. Transfer to a bowl just before serving, mix in the oil and season with salt, a pinch of sugar and pepper. Serve the sliced pork with sauce and coleslaw. This also goes well with fried potatoes.