for at least 15 minutes. You'll notice that the tomatoes will start to sweat liquid -- this is what's supposed to happen.
Pour the canola (or peanut) oil into your skillet to a depth of one inch, and turn your heat to high. Use a cooking thermometer to make sure you bring your oil up to 360 degrees.
Having a high temperature before you put in your battered green tomatoes is really important -- it's what makes them crisp, and helps them to color really beautifully.
Meanwhile, in a paper sack or gallon freezer bag, mix the flour and cornmeal.
In a bowl, mix the egg with a fork, then pour in the buttermilk and mix.
Put the slices of green tomato into your flour/cornmeal mixture and turn to coat. I usually do all of my tomato slices before moving on to the next step.
See how the flour/cornmeal sticks to the tomatoes? This is because of the liquid that comes to the surface because of the salt and sugar.
Now place the green tomato slices into the egg/buttermilk mixture, and then BACK into the sack to coat them with your flour/cornmeal mixture. Shake off the excess.
This Is What They Look Like Just Before You Fry Them