In a large bowl, mix the yeast, sugar and water. Let sit for a few minutes or until it is bubbly. Whisk in the oil, yogurt, and egg, if using.
Add 2 cups of the flour and mix with a wooden spoon. Add enough flour to form a stiff, non sticky dough.
Turn the ball of dough out onto a lightly floured surface and knead the ball of dough for about 3 minutes. Add flour to keep from sticking. The dough should be smooth and very soft but not sticky. Try not to use too much flour, as this can make the dough too dry and stiff. Your Naan will be tough.
Cover the dough in the bowl with plastic wrap and let it rise until double in size (about 1 hour). After it rises, gently flatten the dough into a disc and cut it into 8 equal pieces. Shape each piece into a small ball.
Heat a large, cast iron skillet over medium heat. No need to grease it. Work with one ball at a time, roll it out until it is about 1/4 inch thick or approximately 6 inches in diameter. Uneven shapes are good, they make it more authentic. everyone will know it's homemade! Place the rolled out dough onto the hot skillet and cook until the bottom is golden brown and bubbles have formed on the surface. Turn the dough and cook the other side until golden brown. Stack the cooked flat bread on a plate and brush with melted butter and sprinkled with herbs. Cover with a towel to keep warm as you cook the remaining pieces.