Begin by cutting the beef into 1½-inch cubes, trimming any large fat for optimal tenderness. Season the beef generously with salt and pepper, then toss it in flour to coat.

In a large skillet, heat olive oil over medium-high heat. Add the beef in batches, browning each side for about 45 seconds until golden brown. Transfer the browned beef to the slow cooker.

Reduce the skillet heat to medium and add butter. Sauté chopped onions until they soften and become translucent, about 4-5 minutes. Add minced garlic for an additional minute.

Pour a splash of red wine to deglaze the pan, scraping up any browned bits. Let simmer for 1-2 minutes, then add to slow cooker.

In the slow cooker, add chopped carrots, cubed potatoes, beef stock, and fresh herbs. Stir everything together to combine.

Cover the slow cooker and set to low for 7.5 to 8 hours, or high for 3.5 to 4 hours until the beef is fork-tender.

About 15 minutes before serving, stir in peas.

For a thicker consistency, mix cornstarch with cold water and add to the simmering stew until desired thickness is reached.

Stir in butter just before serving and remove bay leaves and rosemary.