I have never made a brisket. Just so you know up front what kind of advice this is likely to be.
I have found in bbq/grilling anything, it is best to Start on the grill, and finish in the oven, if need be ( in case of weather etc). The smoke permeates the meat from the get -go and the meat only absorbs so much, and not any more after the meat reaches a certain cooking temp. When you look at smoked meats, the smoke ring penetrates only so far, not because it canít go any deeper, but because the internal temp has reached this point and doesnít allow anything further. Iím sure there is some chemistry module that explains this. It is acceptable to bake something, and finish on the grill, if it is a barbeque sauce that you are looking to paint or brush on. That isnít what I see you trying to achieve here. If you are going to serve Burnt Ends, Then I suggest you grill a brisket. Rubbed and Dry marinaded.
Then when it is done and cool enough to handle, slice or chunk it against the grain and Toss it again with some more rub and put it into a disposable sheet pan in single layers and back on the grill until it has all turned into burnt ends. WHAT I can not figure, is how to do the 2nd cook without drying the brisket out and keep it moist. Maybe thatís where the sauce comes into play. If the pan is covered, I would think it would just warm up and steam cook, So thatís a dilemma. Maybe you want to try some ways out using a smaller cut of meat or sacrificing a brisket cut in portions to try different methods. If you were to slice it before cooking, then itís a stir fry, and I donít think thatís the best route.
Briskets are available in full packer cuts, point and flats and separate entities. Just make sure you buy one that is not Injected. That discussion has floated around DC before. Itís all too much for me, so I never do anything except look at them at the meat market and move on to some thing more manageable.
Consequently, I never paid attention if one is supposed to Cook with the fat cap on top or underneath. I think that remains controversial. I expect one should not remove the fat.
I tend to avoid dry rubs/ dry marinades, because I donít care for added salt and too much sugar ( you wonít find me brining the Tís-giving turkey, and I still get a moist bird). But in this instance a good rub with plenty of turbinado sugar should be your friend. The slow carmelization that takes place should aid in achieving the burnt ends at about the same slow and low temp rate you grill at. Indirect heat method.
Itís definitely not the same thing, I do dry rubs when making pork ribs, and they always come out good.
The sauce you were served that you liked, sounds more like a Carolina type sauce, which is interesting since you were in KC which is famous for itís own bbq sauce style. It may indeed be an old sauce recipe you were served, more original than the stuff we see on the grocery shelf as KC Sauces which have become too tomatoey and overpowered by hickory smoke in an attempt to be Authentique. I think you had the real deal !!
These are my ideas. if I am talking out of both sides of my mouth, itís because my tongue is salivating.
Note-- new lesson to self. Donít read DC before Breakfast.
Sure, now that I write this, I decide to google a bitó I went for google Images rather than google Recipes. All this means is someone is an artful photographer; itís more manageable with more than the 43 million dozen hits. Hereís two I find interesting--
How To Make Burnt Ends
Smoked Beef Spare Ribs and Burnt Ends Part 1 - Preparation Recipe Video by 007bondjb | ifood.tv
JBís home movies are a hoot. If you pay attín he knows how to cook. Nevermind, that Boy. Heís been saying this for years. He doesnít seem to mean anything by it. His film editing skills havenít improved either. Iíll fast forward to Part 3 -- The Interesting thing is he finishes his Burnt Ends in the Oven after a bbq grill cook. This might work and smell up the house really nice when you have your gathering.
I think this is a great idea for a summer get together. Hawaiian shirts required.