In Europe, there's no such thing as "Boston butt roast" or even "pork butt", rendering even the first steps down the road to international barbecuing vague and perilous. Heck, even the word "barbecue" itself means something totally different.
In addition to describing exactly what cut of meat "pork butt" is (not the ass of a pig), I found this page from The Virtual Weber Bullet's site to be a critical resource for the nitty-gritty of cooking this cut of meat, as well as for the adaptation of the original recipe.
Just one example: the original recipe has you cook the meat up to an internal temperature of 170F. According to TVWB (and Harold McGee), this isn't quite hot enough to break down the collagen properly for pulled pork and you might end up with a tough, unshreddable piece of meat, bad news indeed after cooking something for 3 or 4 hours (you really want an internal temperature of 195F-205F). Stuff like that.
This here's the recipe. I can't imagine we'll need to look any further for a foolproof, doable-in-Europe BBQ oven-pulled pork recipe. I'm in the process of adapting it from here. Though it says Carolina in the original, this is largely what Georgia BBQ tastes like to me, with a couple of tweaks (celery seed and black pepper). Next tweak we'll be doing is adding smoke, if not via actual grill or smoker then via pimenton or liquid smoke or some other smoked something or other. But for now, this is it.
Below, examples of our differing food styling sensibilities. The first one is Mara's preference. I liked the second one because it reminds me of how I feel about barbecue: savage and uncontrolled.
4 tbsp butter
1 1/2 cups chopped onion
3 cloves garlic, chopped fine
1 tbsp prepared yellow mustard
1 tbsp paprika
1 tsp ground cumin
1/2 tsp or more celery seed
1 tsp cayenne pepper
1 tsp ground chipotle chile or chipotle puree
2 cups Heinz tomato ketchup (other ketchups will not yield same result)
1/4 cup raw sugar
1/4 cup apple cider vinegar
2 cups water
1 tsp salt
2 tsp freshly ground black pepper (important! this is the most essential ingredient)
1 tbsp vegetable oil
one 5.0 lbs. (2.3kg) pork butt (Boston pork butt is what they call this in America)
Cook onion and garlic in butter until soft. Add mustard, paprika, cumin and cayenne, cook 1 minute. Add ketchup, sugar, vinegar and water and simmer, covered, 30 minutes. Uncover; simmer 30 minutes. Add salt and pepper.
Heat oven to 350F. Heat oil in large ovenproof Dutch oven or roasting pan; add pork; brown, 10 minutes. Bake, uncovered, in 350F oven 30 minutes. Pour 1 cup of barbecue sauce over pork. Cover pot. Lower to 250F.
Now, according to some BBQ experts, you should bake it for 1.5 to 2 hours per pound, but you're really shooting for this internal temperature of 190F.
In our case, we don't know why, but we were able to bake it for 3-1/2 hours, basting it occasionally, until an instant-read thermometer inserted in middle of roast registered 190F. Under most circumstances, this amount of meat should take at least 5 hours, more like 7.5, but as you can see, ovens are different, so it can't hurt to start using your thermometer after 4 hours or so.
When your internal temperature is where you want it, remove from oven, let rest for 30 minutes. Trim off excess fat. Pull meat apart using two forks. Mix pulled meat with rest of barbecue sauce in a large bowl. Serve on buns with coleslaw.