In a large mixing bowl, combine ground beef, breadcrumbs, milk, onion soup mix, and dried thyme. Mix gently until well combined.
Shape and Brown Patties:
Shape the beef mixture into oval patties. Heat olive oil in a skillet over medium-high heat. Brown the patties on both sides, creating a flavorful crust. Transfer the browned patties to the slow cooker.
Sauté Onions:
In the same skillet, add sliced onions and sauté until golden and caramelized. This step enhances the depth of flavor in the gravy. Transfer sautéed onions to the slow cooker.
Create Gravy Base:
Sprinkle flour into the skillet drippings and cook, stirring constantly, until it forms a golden-brown roux. This will be the base of your rich and savory gravy.
Slow Cooker Assembly:
Place the roux, condensed cream of chicken soup, water, and au jus mix into the slow cooker. Stir the ingredients until well combined, creating a luscious gravy.
Cook to Perfection:
Nestle the browned Salisbury steak patties into the slow cooker, ensuring they are submerged in the savory gravy. Set the slow cooker to low and let it work its magic for 4-6 hours, allowing the flavors to meld and the meat to become fork-tender.
Serve with Love:
Once cooked, serve the Salisbury steak patties atop a bed of mashed potatoes, rice, or egg noodles. Spoon the flavorful onion and thyme-infused gravy generously over each serving.
Cook Notes

Breadcrumbs Texture: Adjust the amount of breadcrumbs to achieve your desired patty texture. More breadcrumbs create a denser texture, while less provides a lighter bite.
Thyme Sensation: Fresh thyme can be used in place of dried thyme for an extra burst of herbal freshness. Add it to the ground beef mixture or sprinkle it over the patties before serving.
Creamy Consistency: For a creamier gravy, substitute part of the water with heavy cream or milk. This variation adds a velvety richness to the dish.