In a large skillet, melt butter over medium heat. Add onion, cover, and cook, stirring occasionally, for 20 minutes or until tender. Uncover, increase heat to medium-high, and cook, stirring frequently, until onion is caramel colored.
Stir in wine and thyme; cook, stirring occasionally, until wine is reduced by half. Stir in broth; cook, stirring occasionally, until broth is reduced by half. Remove thyme; whisk in Dijon, salt, and pepper. Keep warm.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/vidalia-onion-roasted-steaks-recipe/