To make the sauce, bring the apple juice to the boil in a frying pan over a high heat and cook for 1 minute. Add the apples and simmer for 4 minutes or until just tender but still firm. Remove from the heat and leave to cool to room temperature. Stir in the vanilla essence and raspberries.
Place the linseeds in a mini food processor or spice grinder and grind to a coarse meal. Transfer to large bowl and add the wholemeal flour, buckwheat flour, plain white flour, brown sugar and baking powder. Stir to mix well.
To make the waffle batter, combine the egg yolk and buttermilk in a small bowl. Whisk the 3 egg whites in a large bowl until stiff peaks form. Make a well in the centre of the dry ingredients and stir in the egg yolk mixture. Add the egg whites, then gently mix to combine.
Heat a non-stick waffle iron or maker and spray it with cooking spray. Spoon the batter into the iron, spreading it gently. Close the waffle iron or maker and cook for about 2 minutes or until golden brown and crisp. Lift the cooked waffles from the iron using a round-bladed knife. Keep warm while cooking the rest of the waffles. Serve the waffles warm with the apple-raspberry sauce on the side.
Some more ideas…
You can make the waffles partially or completely in advance. For the former, mix the dry ingredients and freeze in a resealable plastic bag. Just before cooking, add the eggs and buttermilk as instructed in the recipe. Or prepare and cook the waffles, then cool them and wrap in foil. Refrigerate or freeze. At serving time, toast in a toaster or under the grill. You can also make the sauce in advance. * Use fresh blueberries in place of raspberries.
Linseed oil is a rich source of omega-3 fatty acids, which help reduce the risk of heart disease and stroke. To make the linseeds' oil and fibre available to the body, the seeds need to be ground.