Start crockpot on low.
Blanch Perl Onions: 30 seconds in boiling water, then straight to ice-water. Cut root ends and squeeze out the centers.
Reserve 20% of the chopped garlic for the mushrooms.
Render bacon in a heavy pan, remove to a paper towel and chop into small pieces when cool.
Brown brisket cubes in small batches. Don't get too many in the pan or they will steam insteand of saute. Drain on paper towels, then move to crock pot.
Drain off anyt excess grease, then brown onions, carrot and garlic. Move to crock pot.
Deglaze the pan with 1/2 cup of red wine. Pour the result into the crockpot.
In two batches so they do not steam: Melt 1 tbsp cup of butter and sautee half of the mushrooms and half of garlic until mushrooms are golden brown. Refrigerate.
Melt the remaining 1/2 cup of butter in the pan, then slowly add flour to form a light roux. Stir this into the crockpot.
Total cooking time will be 8 hours, but adjust seasoning and add mushrooms during the last 30 minutes.