In a small bowl, mix together the salt, pepper, garlic powder, onion powder, Italian seasoning blend and paprika. Stir until well combined.
Season both sides of the steak with the blend and set aside.
In a large skillet, heat 2 Tablespoons of oil over high heat. When the pan and oil are hot, sear the steak on both sides then promptly remove from pan and transfer to slow cooker.
Lower the heat to medium and add the butter and onion. Cook for about 5 minutes or until onions are tender. Add garlic and cook for 1 additional minute.
Add the tomato paste and cook for 1 additional minute.
Slowly pour the beef broth and onion soup mix to the skillet and deglaze the pan.
Carefully pour the mixture over the ribeye steaks in the slow cooker.
Cover and cook on high 2-3 hours or low for 4-6 hours.