Preheat oven to 350 °F (175°c). Pour the raw hazelnuts onto a baking tray and roast for about 10 mins. Shake the pan after 5 mins and keep an eye on them as they can burn fast. Remove from the oven and cool.
FOR THE HOT CROSS BUNS
In a large bowl, add the flour, yeast, spices, salt, and sugar then mix together. Add the dried fruit, cooled hazelnuts, and lemon and orange zest.
Add the oil, milk, and water. Stir really well with a spoon until everything is combined and there is no dry flour visible. It will be a sticky lumpy-looking mess. That's fine.
Cover with a wet dish towel, or cling wrap and leave on the kitchen counter for a minimum of 6 hours and a maximum of 9 hours. Do not refrigerate and do not leave anywhere extra warm. Just normal room temperature is fine. However, if the temperature in your house is consistently above 22 ° C (72 °F) then just leave it for 5 hours.
After the time has elapsed the dough will be swollen and puffy. Dust a clean, dry, work surface with some flour and turn the dough out onto it making sure you scrape the bowl out well. Try not to tear the dough as you're getting out as it will damage the gluten structure that has developed. It will be sticky but that is normal.
Dust the top of the dough lightly with some flour then form it into a rough round and cut into 10 evenly sized pieces.
Shape each piece into a smooth ball using floured hands. I do this by having the ball of dough on the surface in front of me and use my hands to pull down all around, squeezing it tight underneath. Place the buns gently on a lightly floured, or parchment-lined baking sheet. Have them so they all gently touch each other.
Cover with the damp dish towel (run it under the tap then wring it out) and leave for 30 minutes while you preheat the oven to 400 °F (200°C)
After 30 minutes has passed, make the flour and water paste for the crosses. Add enough water to the 5 tablespoons of flour to make a thick pipe-able paste. Remove the towel from the buns, fill a piping bag or piping syringe ( or a ziplock bag with a small cut in one corner) with the paste and pipe a cross shape on each bun.
Place the buns in the oven and bake for around 20 minutes. Once done they should be starting to turn golden and if you tap one on the bottom it should sound hollow.
Remove from the oven and immediately mix up the glaze. 2 tablespoons of sugar with 2 tablespoons of boiling water. Stir until the sugar dissolves then brush the top of each bun really generously.
Transfer to a cooling rack and be sure to eat one while it's hot!