In a small pan over medium heat, add 250ml of the orange juice to 500ml of water, bring to a simmer and poach the chicken breasts.
Remove the chicken from the pan, cool and shred with a fork.
Lay two leaves of the little gem hearts onto each plate. Place an equal amount of chicken in each lettuce leaf.
In a small bowl, combine the oil and vinegar with the remaining orange juice, spring onions and grapefruit segments.
Spoon equal amounts of the vinaigrette over each lettuce leaf.
Season with salt & pepper if desired.
Wrap lettuce leaf around chicken mixture and eat by hand.