how long do I cook an 19lb bone-in prime rib?

Answer 1

It'll be a while...

1. Set the oven as low as it goes (most likely 200 degrees, but mine goes down to 170)
2. Rub the roast with canola oil (or veg oil)
3. Liberally salt and pepper that roast
4. Put the roast in a glass (or metal) 9x9 dish – preferably glass
5. Cook in the oven until the interior temp reaches 118 degrees (you NEED an instant thermometer – if you don’t have one, you can get one at the grocery store for ~$7). This should take at least an hour depending on the size of the roast (a multi-pound roast could take a few hours)
6. Remove the roast from the oven, and cover (loosely) with foil – think “tent.” This is the resting period, and is important
7. Crank-up the oven to 500 degrees
8. Heat the oven for 15 minutes
9. Pop the roast back-in the oven for ~15 minutes for a crust to form
10. Remove and rest for 10 minutes (or so)
11. Eat

Note: if you have a small roast, and still want it medium-rare, then drop the initial temp to 115 or 112 (for a really small roast), but still to the 500 degree part – the crusty outside is the best part.

Here’s my roast inspiration: http://www.foodnetwork.com/food/recipes/recipe/0,,FOOD_9936_17372,00.html, but all that “terra cotta” pot stuff is a little TOO intense for a roast – it was good for tv, but a little over the top for real-life.

Gravy:
If you want gravy, here’s what you’ll need:

1 can of beef broth
2 tablespoons flour
2 tablespoons butter

When the roast is in the 500 degree part of the process, begin the gravy-making

1. Cook the butter in a saucepan – medium temp
2. When melted, add the flour – make a roux
3. The flour will clump together with the butter – allow it to happen. Then, cook the roux for ~5 minutes until it’s slightly darker than it began
4. When the roast is done at 500, remove the roast to a cutting board and dump the delicious beef juices from the glass dish to the gravy pot (this will be totally awesome – if you have no juices, it’s ok – it will still be good
5. While whisking continually, slowly add the beef broth. As you stir, the flour/butter will thicken the broth. Keep adding broth, a little at a time, until you recognize it as gravy. The flour is a super-strong thickener, and only works when the broth gets warm, so it will get thicker as it warms – be sure to add enough broth (you’ll probably use the whole 15oz can)
6. Check the gravy for seasoning – add salt and pepper as needed

Gravy Variations:

1. If you like mushrooms and onions, you can begin there
2. Slice thin both mushrooms and onions
3. Melt the butter (same amount) and throw-in the onions and mushrooms.
4. Add some salt (1 teaspoon of table salt or 2t of kosher salt). The salt will draw the water out of the mushrooms.
5. Cook the crap out of the onions and mushrooms – until they’re golden brown (that’s the flavor)
6. Then add the flour and proceed as before

Answer 2

I usually start at 200F for a long slow roast and use a thermometer to get the internal temp to about 130F (medium-rare).

Afterward, I crank up the oven to 450F and roast an additiona 10-15 minutes to give the outside some additional color, browning.

For your 19 lb standing rib roast... I'd go 5 or 6 hours before checking the temperature.
If you have a oven safe thermometer, that's probably the best way to ensure you don't over cook... which is difficult to do.

Answer 3

Its all about internal temp. Get a meat thermometer and follow these directions. You are looking at about 4 hours
http://whatscookingamerica.net/Beef/ClassicPrimeRib.htm