Cook the octopus in a pot with plenty of water, semi covered for 40-50 minutes (depending on the size of the octopus).
Once cooked, and cold, cut the octopus, leaving one tentacle aside for garnish.
For the salad, mix the fava beans, lentils, onions and spinach, leaving a few leaves aside for garnish. In a bowl mix the orange juice with lemons, salt, pepper, sesame oil and olive oil. Mix the salad with the dressing. To serve, arrange the octopus over the salad on a plate and garnish with spinach leaves and the tentacle on top.