Boil the potatoes until firm/tender, then drain well and cool to room temperature. Slice the potatoes and store in the fridge until needed. Preheat the oven to 425 degrees F. Place the halibut in a non-stick or parchment-lined baking dish. Drizzle with 1/2 the olive oil and 1/2 the lemon juice; sprinkle with 1/2 the salt, pepper, oregano and paprika. Bake 12 to 15 minutes, or until just cooked through. Heat the remaining oil in a non-stick skillet. Cook the potatoes on both sides until golden brown; sprinkle with the remaining salt, pepper, oregano and paprika. Add the bell peppers and green onion and continue cooking 2-3 minutes more, tossing occasionally. Divide and arrange the potatoes on 4 plates. Top with halibut and serve.