Prick the potato skin and place on a shelf in the oven for an hour.
If you find a raw red onion a bit strong, you can microwave it for a couple of minutes, or soak in boiling water for a couple of mins.
Combine all of the ingredients in a bowl and mix gently together. Season to taste with salt and pepper.
Serve as a filling to the potato.
Notes
Prep Tips:If you love a crispy skinned baked potato, cook it for longer on a lower heat.If you're short on time, the potatoes can be cooked for around 8 mins each (or about 14 mins together) in the microwave.Health Tips:Baking potatoes makes their sugars easier to absorb, so don't choose too big a potato or it will spike your blood sugar, and make sure you eat the skin as the fibre slows digestion down. Eco Tips:You should be able to get all the veg out of packaging. Make sure your tuna is from a sustainable source that at least has the MSC certification. Ideally it should state how the tuna is caught or be 'dolphin-friendly' as the trawler nets used sometimes capture huge amounts of other species.