Heat a saucepan over medium heat and when hot, add the olive oil, then sauté the shallots and garlic for 2 minutes until the shallots become translucent.
Add the wine plus herbs de Provence and cook until the wine is reduced by half.
Add the chicken-based or meat-based demi-glace if you can’t find it. You can also use chicken stock that has been reduced by half. Bring this to a boil and then lower the heat to a simmer.
Add the chopped tomatoes, chervil, parsley, and some salt & white pepper. Cook for a couple more minutes, taste, and adjust seasonings.
It is ready to serve when the sauce is thick enough to coat the back of a spoon.