Slice the green tomatoes into ¼ to ½ inch slices, to your preference. Lightly salt and set aside.
Set up a dredging station with 3 bowls. Add the cornstarch to the first bowl.
In the second bowl, add the buttermilk and beat the egg into it until smooth.
In the third bowl, combine the cornmeal, flour, Cajun seasonings, and salt and pepper to taste.
Heat the vegetable oil in a frying pan or deep skillet over medium-high heat to 350 degrees F. You should have about 1 inch of oil. Do not boil the oil. It is ready when the oil sizzles with a tiny drop of flour added.
Working in batches, dip each tomato slice into the cornstarch, then the buttermilk mixture, then into the seasoned flour-cornmeal mixture.
Fry the coated green tomatoes in a single layer for 1-2 minutes per side, or until golden brown.
Remove and allow to cool and drain on a wire rack or on paper towels. Lightly salt them before they cool.
Serve! I love them with a nice remoulade or with pimiento cheese.