Cut your pork shoulder into 6 to 8 pieces and season liberally with salt and pepper; melt the lard in a large Dutch oven over medium-high heat. When Dutch oven is nice and hot, add the pieces of meat and do not move them until a nice dark crust has formed, about 4-5 minutes. Flip the pieces of meat and sear the other sides until they too, form a nice golden crust.
Transfer the meat to a plate and reserve.
Add onion, celery, bell pepper and raw garlic to the Dutch oven and cook for one or two minutes, just enough for the vegetables to grab a hold of all the delicious flavours that are attached to the bottom of the pan and soften up a little. Add roasted garlic, Dijon mustard, canned tomatoes, olives, herbs and seasoning and stir until well blended.
Put the meat back in, put the lid on and place that in the oven for about 2½ to 3 hours hours, or until the meat detaches very easily when pulled with a fork.
You might want to check from time to time just to make sure you still have enough cooking liquid. If it appears to have gone down too much, add a little bit more water.