TO MAKE THE SAUCE
In a small bowl, combine mayonnaise, honey, sweetened condensed milk, and distilled white vinegar. Mix until smooth and set aside.
TO CANDY THE WALNUTS
Heat a small pan or pot over medium heat. Add the water and sugar and bring to a boil. Boil for 2 minutes and then add the walnuts. Boil for another 2 minutes. Take out the walnuts with a slotted spoon and transfer to a plate or tray and set aside.
TO MAKE THE TEMPURA BATTER
In a mixing bowl, add the egg whites. Use a hand mixer to beat the egg whites until fluffy and bubbly.
Add the cornstarch, baking powder, baking soda, chili powder, paprika, garlic powder, salt, and black pepper and whisk together. Set aside.
TO PREP THE SHRIMP
Toss shrimp in a large bowl with salt and black pepper.
TO BATTER AND FRY THE SHRIMP
Heat oil to 350°F in a wok or pot.
Dip each shrimp in the batter and then let any excess drip off before dropping in the fryer. Make sure not to overcrowd them. Fry in batches if needed. Fry the shrimp until golden brown, about 5 minutes. Take out with a slotted spoon and transfer to a wire rack to let any excess oil drip off.
Transfer the shrimp and walnuts to a deep bowl. Add the sauce (as much or as little as you like) and toss it.
Garnish with sliced green onions and serve with rice. Enjoy immediately for maximum crispiness.