In a pan over medium high heat, add water, sugar and walnuts. Stir and bring to a simmer.
Stir occasionally until the liquid thickens and reduces in volume. This takes about 2-4 minutes.
Remove the walnuts and let it cool on parchment paper.
Sauce
Add all the ingredients for the sauce to a bowl and mix well. Set aside for later.
Shrimp
Rinse the shrimp, pat dry and season with salt and pepper.
Make the batter by whisking the egg yolk until its foamy. Then add the cornstarch. Stir until you well combined.
Add the shrimp and mix well until shrimp is coated with the batter.
Heat up a pot of oil over medium heat. Once it's hot enough, add the shrimp one by one– make sure each shrimp is coated with the batter.
Cook in batches making sure not to overcrowd the pot.
Remove after frying for 3-4 minutes or until it's fully cooked. Fry until all the shrimp are cooked. Double fry all the cooked shrimp at the same time for another 3-4 minutes for crispy shrimp.
Let it cool on a cooling rack for at least 5 minutes before mixing it with the sauce and half of the walnuts. Garnish with the other half and minced green onions. Serve and enjoy!