It would help to have a smoker but you can still do a great brisket in the oven. Before I bought a house and my offset smoker, I had to do briskets in the oven, the only thing they really missed out on was a good smoke flavor (and burnt ends) as liquid smoke just not the same. Even today, I’ll start briskets on the smoker for about 6 hours and then wrap them in foil to be finished inside.
The two recipes look reasonable, but there are a few quibbles. If you want a real Texas brisket, start with a whole untrimmed brisket, usually in the 12-14lb range. Trim the fat down to about 1/4 inch to help form a nice bark on the outside as it cooks. A full size brisket will fit into most ovens and isn’t more work (more time, not more work) as doing a small one. Of course, I can’t imagine cooking only a partial brisket, that’d just be wrong. Keep in mind that cooked brisket freezes nicely.
At 4-5lbs, the briskets in the recipes are likely only the flat. Whole briskets consist of two separate muscles, the flat and the point (aka the deckle). The flat is the leaner tougher part, the point the fattier more tender section.
Fix the rub to your liking, at minimum you will want to use salt and black pepper. A lot depends on how much of the flavor you want to cook into the meat or if you want to let your sauce do the talking. I like the rub to carry most of the flavor and I use a homemade mix of brown sugar, salt, paprika, and black pepper. I’ll rub the brisket down the night before and wrap it tightly to let the spices set.
Cooking time: Texas cooking is low and slow. If I were to do a whole brisket in the oven, I’d use a similar temperature pattern as I do on the pit, start at about 300 - 350 for about 2-hours then let the oven cool and cook at about 210-220 for the remainder.
A whole brisket takes about 45 minutes to an hour per pound to cook. You want the internal temp to about 190 so that the collagen and other tissues are properly broken down. Keep in mind your brisket temp will rise pretty steadily to around 160 or so, but then you will hit the stall, the temp just stays there and won’t go up. Be patient, after several more hours it will start climbing again.
I’d recommend potato salad and pinto beans on the side, maybe some fried okra, too. Enjoy!