In a dry skillet over medium heat, toast the fennel seeds for about 2-3 minutes, or until fragrant. Remove from heat and let cool slightly. In a small bowl, combine the toasted fennel seeds, smoked paprika, salt, and black pepper. Mix well.

Pat the ribeye steaks dry with paper towels. Rub the olive oil over both sides of the steaks. Generously coat both sides of the steaks with the fennel seed and paprika mixture, pressing gently to adhere.

Heat a large skillet or cast-iron pan over medium-high heat. Once hot, add the ribeye steaks. Sear the steaks for about 4-5 minutes on each side for medium-rare, or until they reach your desired doneness. Use a meat thermometer for accuracy (135°F for medium-rare). Once cooked, transfer the steaks to a plate and cover loosely with foil to rest.

In the same skillet, reduce the heat to medium and add the sliced leeks. Sauté in the rendered fat for about 5-6 minutes, or until softened. Add the butter and continue cooking until the leeks are tender and slightly caramelized, about 3-4 minutes.

Pour in the chicken broth and bring to a simmer. Cook for an additional 5-7 minutes, allowing the flavors to meld. Stir in the chopped tarragon and lemon juice. Season with salt and pepper to taste.

Slice the ribeye steaks against the grain. Spoon the tarragon-infused confit leek gravy over the sliced steaks. Serve immediately with your choice of sides.