Use a small serrated knife to cut the skin and all the white pith from the grapefruits and oranges and discard. Then, use the knife to slice between the membranes of the grapefruit to loosen the segments and place in a bowl. Slice the oranges and place with the grapefruit segments into a bowl.
Squeeze any remaining juice from the membranes over the fruit. Stir in the maple syrup and chill until required. Serve with yogurt and a scattering of pumpkin seeds.
Once prepared this can be stored in the fridge for up to 4 days.