Directions 7 steps | 110 Minutes
Measure and prep all ingredients. In a saucepan, heat the 4 cups of stock to a simmer.
Cook the mirepoix. Melt the butter in a medium saucepan over medium heat. Add the chopped onion, carrot and celery. Cook the mirepoix until the vegetables are softened and golden, 6-8 minutes.
Make the roux. Sprinkle in the flour and stir together with the mirepoix. Cook until the roux is dark golden brown, about 7-10 minutes, stirring often.
Add the stock. When the roux is ready, slowly pour in the warm stock while whisking vigorously and constantly to ensure the sauce is lump-free.
Add the tomato purée and herbs. Whisk in the tomato purée, bay leaf and fresh thyme. Bring to a boil. Once boiling, reduce the heat to a simmer and simmer, uncovered, until the sauce reduces by a third, about 30-45 minutes. Stir occasionally. Season the sauce to taste with salt and pepper.
Strain the sauce. Strain the sauce through a cheesecloth or a fine mesh strainer. Discard the solids.
Serve or use immediately. Enjoy!