Use BBQ for both searing and slow-roasting beef When I make roast beef in the kitchen I typically have these two cooking steps:


Sear on all sides in a frying pan on high(ish) heat;
Slowly roast it in the oven on low(ish) temperatures.


I've varied the temperature in step 2 from 160 degrees celsius down to 80 degrees (about the lowest temp my oven can consistently provide). I've found that the closer (lower) I get to 80 degrees, the better the result.

I want to bring this process to my BBQ now, preferably doing both steps using the BBQ itself. I'm unsure how to deal with the fact that the BBQ should be rather hot for step 1, yet a lot cooler for step 2. 

From experience I know that the heat I'd want for step 1 would at a minimum lead to 180 degrees on my BBQ when the lid goes on (or higher if I'd fail to reduce air flow). 

The only workarounds I could think of:


Do step 1 in the kitchen with a frying pan (feels like cheating / will reduce BBQ-flavor);
Do step 1 on a lot of coal, and remove some coal before moving to step 2 (feels wasteful);


Do you guys have any suggestions on how to handle this?

Some more details:


I have a Weber BBQ with lid and built-in temperature monitor;
I have a meat thermometer to measure the core temp of the meat as it roasts;
I use indirect heat for step 2 by having the coal on the sides and the meat in the middle, and intended to use direct heat in step 1 by placing the meat over one of the sides;
I have a chimney to quickly get fresh coal started;
In the Good Eats episode on tuna, Alton Brown mentioned that you want as hot of a fire as possible, and that you could cook directly over the chimney starter, once the coals are going:


  As for the fire, well, it's hot. It's real hot. Just take a look. It's like a jet engine down there. Now the normal thing to do would be to distribute those coals across the bottom of the grill and get to cookin'. But, um, I don't want to dissipate the heat. I don't want to spread it out. I want to keep it concentrated. I want to cook on a jet engine! And ... it's ... my jet engine so I say we'll cook on the jet engine.


He then put a grate over the top of the chimney starter, and cooked his tuna.

In your case, you could sear the outside of the roast, move it to the side, then dump the coals into your grill for a two-level fire, and  then put the meat over on the cold side.  It's not all that different from what you were already doing, but it should give you a hotter initial sear.