Add into a cup 150ml of water and dilute into it the vegetable stock and the mustard. Add the thyme, paprika and coriander and mix well. Keep aside.
Place a large pot or casserole (with lid) on medium-high heat and pour 2 tbsp of oil along with the butter. Once melted add the pork loin and sear all of its sides until nicely browned. Add the potatoes, carrots, onions along with the rest of the oil (2 tbsp) and we sauté for a minute or so.
Pour the brandy and deglaze. Once the alcohol has evaporated pour the beer along with the mixture of the 150ml water, cover with the lid and bring to a boil. Simmer at low heat for 80’ while gently stirring every 10’ and making sure that the liquid has not completely evaporated. If needed add some more water.
10’ before removing from the fire, pour the lemon juice and season with the salt and pepper.
Remove from the fire and place the pork loin on a cutting board and slice it in medium thickness slices, about 7mm. Serve with the potatoes and the vegetable while pouring some of the sauce on top and garnishing with the parsley.