Add the yeast and sugar into the water. Mix well and leave for 10 minutes for the yeast to activate.
Break the eggs into a bowl and add the vegetable oil. Beat well until the mixture is smooth and frothy.
Put the flour into a bowl and make a well in the centre. Sprinkle on the salt and add in the egg mixture, the vinegar, the chia seeds and the yeast/water mix. Stir well with a spoon until you have a thick batter which drops sluggishly off the spoon
Pour the batter into a lightly-greased 22cm x 11cm (8½" x 4½") loaf tin. Spread evenly into the tin. Cover with oiled film or place in a large plastic bag in a warm place to allow the mixture to rise. Leave for about an hour.
Once the mixture has risen, bake at 190°C/375°F fan oven, 220°C/430°F for 25 minutes. First 15 mins on lower heat, next 10 mins on both upper and lower heat.