For the Fish:
Season the fish fillets with salt and pepper. Pour 3 tablespoons of oil in a saute pan over medium-high heat. When the pan is hot, but not smoking, place fish in pan skin side down, gently pressing on the fish so it does not curl up. From this point turn down the heat to medium and do not touch the fish. The skin will become crispy and release itself from the pan. Cook for 4 minutes on the skin side, and turn the fish over, cooking for 2 more minutes or just until done. Keep warm.
For the Ragout:
In a medium saute pan, heat 2 tablespoons of oil over medium-high heat. When hot, add the potatoes and onions, sauteing them until warmed through and a little color has appeared on the potatoes. Add the artichokes and olives and cook another 2 minutes. Pour in the chicken stock and season with salt and pepper. Continue cooking until the potatoes are tender. Drizzle remaining1 tablespoon of olive oil into the ragout before plating. Serve warm.
For the Sauce Vierge:
Cut the lemon in half. Squeeze 1 tablespoon of juice from half of the lemon into a bowl, removing any seeds that may fall into the bowl. Slice the other half of the lemon into thin slices, and place them in the bowl. Add the garlic, tomatoes, and parsley to the bowl. Add 2 tablespoons of olive oil and season with salt and pepper, to taste. Stir to combine.
Spoon the ragout evenly into 4 warm bowls, or deep plates. Top the ragout with the fish, skin side up. Drizzle the sauce on top of the fish and serve immediately.