Preheat the oven to 175°C (345°F/Gas 3-4) and grease and line a 20 x 9 cm (8 x 31/2 inch) loaf (bar) tin with baking paper.
Combine the flour, ground flaxseeds, chia and sunflower seeds, pepitas and salt in a bowl and mix until combined.
In a separate large bowl, use an electric beater to beat the eggs for about 2 minutes - they should be pale and fluffy. Stir in the vinegar, butter, coconut milk, stevia and water. Pour the wet ingredients into the bowl with the flour mixture and stir well to combine. Spoon the mixture into the prepared loaf tin and bake in the oven for 40 minutes, or until a skewer inserted in the centre of the loaf comes out clean.
Turn out onto a wire rack to cool.
This loaf will keep for 1 week in the fridge or 2 months in the freezer.