Where do you go to find a recipe when Food 52 does not have one for pickled green tomatoes?

Perfect: http://www.puttingupwitherin.com/2015/09/01/habanero-ginger-green-tomatoes/

I agree you can't go wrong with Mrs. Wheelbarrow, but I also think Punk Domestics is a good resource: http://www.punkdomestics.com/search/node/pickled%20green%20tomatoes

I've had great success using www.foodblogsearch.com to find many recipes including Food52 recipes. Best of luck!

Try roasting them at a high temp, then freezing. Did this in desperation one year when an early frost was forecast and now always do some.

Another fun link, featuring Food52's own Mrs. Wheelbarrow:
http://www.splendidtable.org/story/when-pickling-spring-vegetables-choose-your-water-salt-and-vinegar-carefully

Here's a recipe you can try;
https://food52.com/recipes/34662-green-ajvar-green-tomato-relish

I'm curious, this time of year, why not let them get ripe? There are a lot of recipe sites out there, generally not very dependable; epicurious.com usually isn't too bad.

Here's one from the NY Times:

http://cooking.nytimes.com/recipes/1016825-pickled-green-tomatoes

I consider them to be a fairly reputable source of food recipes.

I found this recipe using a search engine, one that starts with a G.

Easy! Click on the search glass icon, then type "pickle" or "pickling" in the search box.
Here's one:
https://food52.com/blog/7098-quick-pickling-101

I have a copy of the community cookbook, "Charleston Receipts." It has three recipes for green tomato pickle each making 8 pints. The last calls for a calcium chloride solution. Here is the first recipe from Mrs. Edmund Rhett Heyward:

1 peck green tomatoes
2 quarts onions
2 quarts vinegar
1/2 tablespoon cayenne pepper
1 tablespoon dry mustard
1 teaspoon turmeric
2 pounds brown sugar
1/2 pound white mustard seed
1/2 ounce ground mace
1 tablespoon celery seed
1 tablespoon ground cloves
1/2 cup olive oil
Slice tomatoes and onions very thin. Place on large platters and sprinkle with salt. Let stand overnight. Drain through colander. Add one quart vinegar to vegetables and boil slowly until tender and clear. Drain. Mix sugar, mustard seed, celery seed and cloves with [second quart of] vinegar and boil 5 minutes. Mix drained vegetables with cayenne pepper, mustard and turmeric and add to vinegar mixture. Mix well, add olive oil and seal in jars. Yield: 8 quarts.
The other recipes include one for Sweet Green Tomato Pickle with cabbage and onions, and similar spicing but adds ginger. It includes one cup salt which, I don't see int the first. The last calls for a calcium chloride solution. There is also a recipe for chow-chow, containing cabbage, green tomatoes and bell peppers. You could private message me through my profile page if the other recipes interest you! Charleston Receipts is considered a good cookbook. I'm sure Joy of Cooking must have some recipes too, just not finding my copy at the moment and must get ready for Father's Day brunch!