Original guidance came from this recipe from Delicious Istanbul.
I suggest using a kitchen scale for more accurate measurements. I have included cup equivalents, but can't personally attest to the accuracy of the conversions.
The original recipe calls for pekmez (aka grape molasses). I didn't have this hanging around, so I used a mixture of pomegranate molasses and regular dark molasses. The molasses helps to stick the seeds to the dough and form a golden brown crust, but the flavor isn't really perceptible in the finished product, so choose whatever you've got on hand.
500 g all-purpose flour (3 cups + 2 Tbsp)
300 g water (1 1/4 cups)
7.5 g active dry yeast (2 1/2 tsp)
7.5 g fine sea salt (1 1/8tsp)
70 g sesame seeds (1/2 cup)
60 g molasses (1/4 cup)
Step 1: making the dough
In a large bowl, stir the yeast into the water to dissolve it. Add the sea salt and about 1/3 of the flour to make a thin batter (like pancake batter). Continue to stir in about 1/3 more of the flour. To slowly incorporate the remaining flour, knead it in with your hands, adding flour as the dough absorbs what is in the bowl. Knead for about 10 minutes total.
Cover the bowl with plastic wrap and put in the fridge overnight.
Step 2: shaping the dough
Punch down the dough and divide into 8 equal pieces. Shape each piece into a nice round ball and dust with just a little bit of flour. Cover dough balls with a clean kitchen towel and let rest for about 15 minutes.
Roll each dough ball into a long snake, moving hands from the center out to the edges to stretch it (like you use to do with Play-dough). If you are having trouble stretching it, there might be too much flour on the dough or surface. Wet your hands a tiny bit to make it easier. Make the snake as long as possible. I found the best ones I made were close to 3 feet long. Lift the snake from the center and twirl the ends around each other. Connect by lacing the loose ends of the twirl through the loop and pinching them together, making a large ring. Set aside and repeat with each piece of dough. It took me a couple rounds to get the hang of it, so don't get discouraged.
Step 3: the double dip
Toast the sesame seeds in a dry pan on high heat. Stir constantly to avoid burning (Mom, don't walk away from the stove!) The seeds will begin to pop and turn a light brown. If anything, you want to under-toast them since they will be going into a very hot oven later. Set aside in a shallow bowl.
In another shallow bowl, mix the molasses with an equal part water to thin it out. Dip each ring in the molasses, flipping it to coat completely. Place the ring in a colander to drain excess molasses. Continue with all the rings. It is ok to pile them up in the colander, they won't stick.
Remove each ring, one at a time, from the colander. Stretch the ring as you do this, until it is about 6 inches in diameter. Dip it in the sesame seeds and flip to coat both sides well. Place on a baking sheet lined with parchment paper. I needed 2 baking sheets, 4 rings on each.
Step 4: bake off!
Preheat the oven to 465 degrees fahrenheit. Put a pan of boiling water on the bottom rack of the oven (to create steam in the oven, a desirable environment for forming a quick rise and nice crust on the simit).
Let the rings proof (rest in a warm environment, like top of the stove) for at least 20 minutes. If you don't have room in your oven for both baking sheets, leave one to proof while the other bakes.
As you set the baking sheet in the oven, splash about 1/4 cup of water in the bottom of the oven and shut the door immediately (more steam!). Bake for 10 minutes. Remove the pan of water from the oven and continue to bake for 10 more minutes, until the rings have formed a beautiful, reddish golden brown crust.
Repeat with the other sheet.
Eat at least one as soon as it is just cool enough to shove in your mouth.