In a large bowl, sprinkle the yeast and sugar over the water and let stand for 5 minutes, until foamy. (If it doesn't foam, the yeast is inactive; toss it out!) Stir in the flour, salt, oil, yogurt and egg and stir until the dough comes together, then knead until you have a soft, pliable dough. Cover with a tea towel and let rise for an hour or two. (If you want to make it in advance, cover and store in the fridge to slow down the rise.)
Pinch off pieces the size of an egg or two (depending how big you want your naan), and roll into a thin circle or oval — don’t flour the surface, it needs to be tacky enough to grip slightly, like a post-it note. Preheat a heavy skillet over medium-high heat and drizzle generously with oil and a pat of butter, or add a spoonful of ghee and rotate the pan to coat the bottom as it melts.
Peel each piece of dough off the countertop and lay it in the hot skillet. Cook until it grows dramatic bubbles on one side, then flip and cook until golden on the other. Stack on a plate as they cook, and bring them to the table warm. Makes about 8 naan.