Make the buttermilk ranch: In a medium bowl, whisk together the sour cream, mayonnaise, buttermilk, lemon juice, dill, pepper, onion powder, garlic powder, and salt. Refrigerate until ready to serve.
Make the fried tomatoes: Slice the tomatoes into ½-inch (1 ¼ cm) -thick slices. Lightly season the tomato slices on both sides with salt.
Place ½ cup (60 G) of flour in a medium shallow bowl.
In a separate bowl, combine the cornmeal, remaining ½ cup (60 G) flour, the cayenne, garlic powder. and the 1¼ teaspoons of salt and mix with a fork to combine.
In another medium, whisk the eggs and buttermilk together.
Dredge each tomato slice in the plain flour, then in the egg mixture, then in the seasoned cornmeal mixture.
Pour ½ inch (1 ¼ cm) of canola oil into a large skillet. Heat over medium-high heat until the temperature reaches 400ºF (200ºC).
Working in batches, fry the tomatoes for 1 minute on each side, until golden brown. Do not overcook the tomatoes, or they will become mushy inside. Transfer the fried tomatoes to a paper towel-lined baking sheet and season with salt.
Serve the fried tomatoes with the buttermilk ranch.