Combine warm water (100-110°F/38-43°C), sugar, and instant yeast in a small bowl. Stir gently and let sit for 8-10 minutes until foamy and bubbly.
In a large mixing bowl, whisk together the all-purpose flour and salt. Create a well in the center of the flour mixture.
In a medium bowl, whisk together the plain yogurt and olive oil until smooth.
Pour the foamy yeast mixture and the yogurt-oil mixture into the well in the flour. Stir from the center outward until a shaggy dough forms.
Lightly flour a clean work surface and turn the dough out. Knead for 3-4 minutes until smooth and elastic.
Grease the mixing bowl with olive oil, place the dough ball in it, turning to coat all sides. Cover with plastic wrap or a damp towel and let rise in a warm place for 60-90 minutes until doubled in size.
Punch down the dough and turn it out onto a lightly floured surface. Divide into 6-8 equal pieces, roll each into a smooth ball, cover with a damp towel, and let rest for 10 minutes.
On a lightly floured surface, roll each ball into an oval or teardrop shape about ¼ inch (6mm) thick.
Place your cast iron skillet or heavy-bottomed pan over medium-high heat for at least 5 minutes until very hot.
Carefully place one rolled naan onto the hot, dry skillet. Cook undisturbed for 1-2 minutes until bubbles form and the bottom has golden-brown char spots. Flip and cook the second side for 1-2 minutes.
Remove naan from skillet and immediately brush generously with melted butter or ghee. Sprinkle with a pinch of salt and optional minced garlic or fresh herbs. Stack and cover with a kitchen towel to keep warm.