Mix the eggs and the sherry in a wide bowl. Combine the flour, cornstarch, salt and pepper. Dip the chicken in the egg wash and shake off the excess. Dust the chicken with the flour-cornstarch mixture on both sides.
Heat a little less than half of the vegetable oil in a skillet or wok until it's close to smoking. Fry the chicken until golden brown. Remove and hold in a 200 oven.
To make the sauce, add the remaining oil to the pan or wok and heat over medium-high heat until it ripples. Add the onions and celery, and cook until browned a little.
Add the remaining flour-cornstarch mixture. Cook while stirring until a light-brown roux forms.
Add the stock, soy sauce, and the garlic. Cook until the garlic is aromatic. Turn the heat off.
Mix the cornstarch with a tablespoon of water till well blended, and stir into the sauce.
Add salt and Tabasco to taste. If you like, toss the chicken with the sauce, or serve on the side. It's equally bad either way.