Cut the tops and bottoms off the oranges and cut away all the peel and white membrane from the outside of the oranges. Cut them into slices and arrange on two plates. Drizzle with a bit of olive oil and season with salt and pepper and a pinch of cayenne. Smash each olive with the bottom of a glass and remove the pit. Chop the olives roughly. Combine with the avocado and red onion. Season with salt, a squeeze of lemon and a bit of olive oil. Divide the olive and avocado mixture between the two plates and garnish each plate with the pumpkin seeds.