In a medium bowl, dissolve the active dry yeast, 1 tsp sugar and warm water. Let it sit for about 10 minutes until bubbly.
In a large bowl, whisk together the remaining sugar, flour and salt and set aside.
Once the yeast is bubbly, add the yogurt and olive oil and whisk to combine.
Pour the yogurt mixture into the dry ingredients and mix the dough together with a fork.
When the dough starts to come together, knead gently by hand into a soft, slightly sticky dough. Don’t over knead. You may need to flour your hands if it’s too sticky.
Place the dough in a lightly oiled large bowl and cover with a damp kitchen towel. Let sit in a warm place until it’s doubled in size. This may take up to 3 hours.
Dust a work surface with flour and dump the dough out onto the surface.
Shape the dough into a circle and cut into 6 equal portions. Roll each portion of dough into a ball and cover with a towel.
Warm the cast iron pan over medium-high heat until very hot.
Using a rolling pin, roll one of the dough balls into an oval shape about ⅛ inch thick
Gently lay the dough in the dry skillet and cook until the top puffs up, about 2 minutes.
Flip the naan and cook about 1 ½ minutes more until the the bottom is lightly browned and blistered in spots.
Remove the naan from the skillet and brush with melted butter.
Place the naan on a tea towel-lined plate to keep warm.
Repeat with the remaining dough balls. Serve warm.
