Preheat the oven to 200ºc and prepare muffin cases in a baking tray.
First, melt the coconut oil, as it needs time to cool down a bit before using.
In a large bowl, combine the dry ingredients and mix together.
In another bowl, combine the water, vinegar and coconut oil. Add the eggs and mix well, then add this to the dry ingredients.
Finally add the sun-dried tomatoes, spinach, onions and feta, fold together to combine but don't over mix.
Spoon into the muffin cases and bake for approximately 35 minutes until cooked through (test with a cocktail stick - if it comes out clean, they're done!)