You need to make sure you have an active sourdough starter to use for this naan. It should have been fed and then risen until bubbly. 

• Mix the sourdough starter and water. Use a kitchen scale to measure the water and bubbly (active) sourdough starter and add to a large bowl. Stir well with a fork.

  150 grams sourdough starter (3/4 cup), 235 grams filtered water (1 cup)
• Add remaining wet ingredients. Then add the remaining wet ingredients - olive oil and Greek yogurt - and mix again.

  52 grams olive oil (1/4 cup), 120 grams plain Greek yogurt (1/2 cup)
• Add the dry ingredients. Add the all-purpose flour, whole wheat flour, granulated sugar, and sea salt. Mix well with a fork and then use your hands to squeeze the ingredients together. The mixture will be shaggy.

  Cover with a damp towel and let the shaggy sit for 45 minutes. (Be sure to set a timer.) This is the AUTOLYSE.

  390 grams all-purpose flour (3 1/4 cups), 33 grams whole wheat flour (1/4 cup), 13 grams granulated sugar (1 Tablespoon), 12 grams sea salt (2 teaspoons)
• Start stretch and folds. After 45 minutes, start the STRETCH AND FOLDS. Use your hand and lift the dough up on one side, stretching it upward, and then punch into the center of the dough. Turn the dough and repeat. Continue this process for about 30 seconds.
• ADDITIONAL STRETCH AND FOLDS: I recommend doing additional sets of stretch and folds if time permits. Do these every 30 minutes for 3-4 more times to further the gluten development. A bench scraper is an excellent tool to assist with the stretch and folds.
• Let the sourdough naan dough rise for 6-8 hours, or overnight. It should almost double in size and appear soft on top. Small air bubbles may appear as well. This is the BULK RISE (or bulk fermentation). 
• **If you have time, I recommend placing the sourdough in the refrigerator for 24 hours. This will develop a more sour flavor which we enjoy. You'll want to place the bowl of dough on your countertop for a couple of hours before forming naan bread.

  Add a bit of olive oil to the top of the dough and then add cling wrap to the top of the bowl.
• Form the naan bread. Add a light dusting of flour to a baking mat or clean surface. Remove the bread dough to the mat and divide the dough into about 10 equal pieces. Then use your hands to form balls of dough and try to coax each ball to have smooth top, using your hands to rotate the shapes on a clean surface.

  Place a towel on the dough balls and let rest for 20 minutes.
• Roll out the dough. Use a lightly floured surface and a rolling pin to roll out each dough ball into a round or oval shape.
• Grill bread. Preheat a cast iron skillet over medium-high heat. As each shape is formed, place in the hot skillet cooking for a couple of minutes on one side. Then flip to cook on the other side. Cooking time will vary.
• Cool. Transfer each naan bread to a clean towel. Brush both sides with melted butter.