Heat 1 tablespoon of olive oil in a large cast-iron skillet over medium-high heat. Add the beef and cook until browned, about 3-4 minutes per side. Transfer the beef to a plate and set aside.

Reduce heat to medium and add the remaining 1 tablespoon of olive oil to the skillet. Add the chopped onion and cook until softened, about 3-4 minutes. Add the minced garlic and cook for a further minute, until fragrant.

Add the chopped kale to the skillet and cook until wilted, about 2-3 minutes. Add the cherry tomatoes and cook for a further 2 minutes, until they start to release their juices.

Add the beef broth, thyme, salt, and pepper to the skillet. Stir to combine and bring to a simmer.

Add the browned beef back to the skillet and stir to combine with the kale and tomato mixture.

Reduce heat to low and simmer for 10-12 minutes, or until the beef is cooked through and the sauce has thickened.

Stir in the butter until melted and season with additional salt and pepper if needed.

Serve hot, garnished with chopped fresh herbs if desired.