Season both sides of the pork shoulder with salt, pepper and smoked paprika.
Place a large pan or skillet on medium-high heat. Add the olive oil and place the pork. Sear on all sides until brown. Remove the pork from the pan the set aside on a tray.
In a food processor, blend the garlic, onions, celery and carrots into a thick paste (don’t add water). Add the paste to the hot pan that you seared the pork shoulder in. Stir and saute for 2 minutes.
Add the fresh thyme (put the leaves only and discard the stem), bay leaves and tomato concentrate to the pot and cook for a further 2 minutes.
Pour the bottle of red wine in, stir and bring to a simmer.
Put the browned pork shoulder back into the pot and submerge into the sauce.
Reduce the heat to low, and cover the pan tightly (first with aluminium foil then the cap).
Cook for at least 7 to 8 hours or overnight. Until pork is very tender and easily pulled apart with a fork.
Shred the pork with 2 forks and discard the bone and pieces of bay leaf.