Add vinegar, water, salt, sugar, red pepper flakes, garlic and dill. Close the lid and shake to distribute ingredients. (Liquid will not cover green tomato slices. But don't worry, in a couple of hours the salt will draw liquid from the tomatoes.)
Place the jar in the refrigerator and remember to shake it once or twice in the next few hours. In about 6 hours, you'll have delicious, crispy pickled green tomatoes.
Video
Notes
If using larger tomatoes, cut into small wedges to fit the jar.
These stay crisp in the fridge for up to 1 month.
I reuse the brine once—just strain and reuse within 2 weeks.
A few red streaks on tomatoes are fine; just avoid fully ripe ones.