I brined it last time I cooked it and I probably will again, but am considering a crust or a rub.
i would definitely brine it for at least 4 hours. then just roast it with herbs or glaze with your favorite preserves, covered, on about 300. then crank the heat to 400 and uncover for the last part of cooking to get a nice crust on the top layer, being careful not to burn the preserves (if using).
How long should I cook it? The things I am reading are so mixed. It is of uniform thickness, is already tied, and is more round than flat. Some websites say pork loins generally cook in an hour regardless of weight other says anywhere from 25-40 minutes per pound, which is much different.
a good rub would be 2 Tbsp. paprika, 1 tsp. onion powder, 1 tsp. salt, 1/4 tsp. cayenne, 1/2 tsp. cumin, 1 Tbsp. brown sugar, and 1/4 tsp. granulated garlic. i mix this with a bit of oil to make a paste and roast away. it's good on chops, chicken, and even steak.
pork can be confusing. i will tell you that the health department says to cook it to an internal temp of 185. now that the disclaimer is out of the way.....
i cook mine to 160-165. pork tenderloin can be cooked to a much lower internal temp but pork loin i like to cook to 160-165. carry-over cooking will cook it up to 165-170. this temp allows it to be tender and juicy but not so pink that people freak out over it looking "raw."
some people cook their pork loin roasts to an even lower temp, but i do find the freak-out factor to just be too annoying and go ahead and cook it to 160-165. as long as you brine it and cook it low and slow, you should be fine on juiciness and tenderness. make sure to let it rest for at least 20 minutes after it's out of the oven before slicing. you could choose to brown it off first, before roasting it low and slow, or crank the heat towards the end of cooking and brown it that way.
time will vary according to your oven and how fast or slow it cooks and the type of pan you are roasting it in. it will definitely be under 2 hours.
Butterfly it - stuff it with sauted spinach, parmesan cheese, breadcrumbs and prosciutto - roll up and tie w/butcher string - roast 375 to 160-165 degrees internal....it is delish!!!!!!
I would butterfly it, stuff it with something tasty and baste with marmalade for the last half hour.