As is usual with these emblematic recipes, I keep my distance; this is not "the" recipe for eggs meurette, just one among many, my own version. What's more, I reckon there must be as many versions as cooks in Burgundy...
In this recipe, everything can be prepared in advance, even the day before. But it's wiser to fry the bread and thicken the wine sauce at the last minute.
The great chef Bernard Loiseau used a carrot purée rather than cornflour to thicken the sauce.
In a restaurant near Meursault I tasted a version with chopped mushrooms added to the onions, which was an excellent idea.
You can also enhance the flavour of the sauce by adding a bouquet garni
to the pan as it comes to the boil, or 1 or 2 cloves of garlic.