Heat one tablespoon of neutral oil in a medium saucepan over medium heat. Add the shallot and cook until caramelized.
1 tablespoon neutral oil, 2 shallot
Add the remaining vegetables and sauté for one to one and a half minutes. Add the tomato paste and cook for 30 seconds, stirring constantly.
2 green onion, ½ celery stalk, ½ whole carrot, 1 whole garlic clove, 2 teaspoon tomato paste
Deglaze the pan with the red wine and cook until reduced by half.
½ cup Pinot Noir or good Burgundy wine
Add the beef broth, reduce the heat to a simmer, and cook for 20-30 minutes, or until reduced by about two-thirds.
4 cup good-quality beef broth
Meanwhile, melt the butter in a clean small saucepan. Add the flour and stir with a spatula until golden to create a roux. Remove from the heat and let cool slightly.
1¾ tablespoon butter, 1½ tablespoon all-purpose flour
Place a fine-mesh strainer over the pan with the roux. Strain the reduced broth directly into the roux, pressing the vegetables with the back of a spoon to extract as much liquid as possible. Discard the solids.
Return the pan to the heat and gently whisk until the sauce is thickened, glossy, and coats the back of a spoon. Taste and season with freshly ground black pepper as needed. Set aside and keep warm.
optional black pepper