Whisk the yeast and 1/2 cup / 110 ml of lukewarm water in a medium bowl to blend.
Set aside for 5 minutes or until the yeast dissolves.
Whisk the remaining water into the yeast mixture.
Combine the flour and salt in a large bowl.
Pour the yeast mixture over the flour mixture, stirring constantly with a wooden spoon until you have a well mixed batter.
The batter will be thick and sticky.
Cover the bowl of batter with a clean dish cloth and set aside in a warm place for 1 to 2 hours or until the batter has risen and doubled in size and small bubbles form.
Add enough oil to a large, deep frying pan to come halfway up the sides of the pan.
Heat the oil over a medium heat to 375°F / 190°C.
Combine the sugar and cinnamon in another large bowl and set aside. Stir the batter to deflate it.
Working in batches and using a tablespoon, spoon the batter one spoonful at a time into the hot oil (you can cook about 8 doughnuts at a time).
The batter will still be thick and sticky so the tablespoon will not fill neatly but will help as a guide to ensure the proportions are similar in size.
Fry for about 5 to 8 minutes or until the doughnuts puff and become golden brown, turning them occasionally to ensure they brown evenly. While frying, the batter will form round, puffy, irregularly shaped doughnuts.
Remove the doughnuts with a meshed or slotted spoon once they are golden and place them on a baking sheet lined with paper towels to absorb the excess oil.
Immediately toss the hot doughnuts in the cinnamon-sugar to coat.
Transfer the coated doughnuts to a warm platter.
Meanwhile, heat the honey in a small saucepan over medium heat until it is hot.
Drizzle the hot honey over the doughnuts.
Sprinkle with the crushed hazelnuts and serve immediately.