if your brisket is alreay corned you can simmer it any number of ways. You should have either the packet of pickling spices that came with it or else use a tablespoon or two of your own to add to the liquid. This would be the time to add the beer and brown sugar... the flavor will concentrate during the simmering. 1 bottle of beer and 1/4 cup of sugar should do nicely. fine tune to taste as you go - as long as the liquid is flavorful, so will the end product.

You can cook the vegetables separately... though I add them to the main pot at the end to gain the added flavor. Tender not mushy is the goal. And a long slow simmer will make the meat tender but easy to slice at the end... same as as using the oven without the glaze.

Good mustard is a must... and Irish mustard sauce is outstanding - recipes abound online. Have some good vinegar - apple or malt - on the table to add to the vegetables, especially the cabbage.

I often use a large electric skillet or roaster oven to make the beef - better control as long as you keep an eye on the level of liquid and frees up the stove. A dutch oven works fine - stove top or in the oven.

Damn - it's barely past breakfast here & I'm dying for a nice corned beef dinner.... LOL