Preheat your grill or a heavy skillet over medium-high heat. Season both sides of the ribeye steaks generously with salt and pepper.

In a dry skillet over medium heat, add the mustard seeds. Toast them for about 2-3 minutes, stirring frequently, until they start to pop and become fragrant. Remove from heat and let cool.

In a small bowl, combine the toasted mustard seeds and smoked paprika. Mix well to create a spice rub.

Rub the olive oil over the ribeye steaks, ensuring they are well coated. Then, evenly press the spice rub onto both sides of the steaks.

Place the seasoned ribeye steaks on the hot grill or skillet. Cook for about 4-5 minutes on one side, then flip and cook for an additional 4-5 minutes for medium-rare, or until desired doneness is reached. Remove from heat and let rest for 5 minutes before slicing.

In a saucepan over medium heat, combine the heavy cream, lemon juice, Dijon mustard, and chopped tarragon. Stir well and let it simmer for about 5 minutes, allowing the flavors to meld together. Season with salt and pepper to taste.

Slice the ribeye steaks against the grain and serve with the creamy lemon-tarragon gravy drizzled over the top. Enjoy your meal!