Shake tomato slices in a paper sack with salt, pepper and flour.
Heat oil over medium-high heat in a black iron skillet. Add tomatoes and garlic. Cook without stirring for about 5 minutes, then, using a stiff spatula, scrape bottom of skillet and turn tomatoes. Continue to cook over medium to high heat, scraping bottom of skillet occasionally to prevent burning. You want the tomatoes which come in direct contact with the skillet to get dark. You should expect some sticking; just scrape hard. Try to resist adding more oil but do so if you must.
When most of the tomatoes have turned olive green or dark brown, about 20 minutes, lower heat to low. Continue to cook, worrying the tomatoes around with the spatula until they are all either brown or olive green. (Don't worry them too much; if you are too worrisome they turn mushy. )
(Old family recipe; garlic and olive oil are my additions. ) Source: Overton Anderson