In a small bowl, stir together warm water, sugar, and yeast. Let sit 5 minutes until foamy. If it doesn't foam, your yeast is dead - start over with fresh yeast.

In a large bowl, combine flour and salt. Add the yeast mixture, yogurt, and olive oil. Stir with a wooden spoon until a shaggy dough forms, then turn out onto a lightly floured surface.

Knead for 8-10 minutes until smooth and elastic. The dough should feel tacky but not sticky - add flour 1 tablespoon at a time if needed. Form into a ball.

Place dough in a lightly oiled bowl, cover with a damp towel, and let rise in a warm spot for 1 to 1.5 hours until doubled in size.

Punch down the risen dough and divide into 8 equal pieces. Roll each into a ball, then flatten and roll into an oval about 1/4 inch thick. Don't worry about perfect shapes - rustic is fine.

Heat your cast-iron skillet over medium-high heat until very hot, about 3 minutes. Cook one naan at a time for 1-2 minutes per side until puffed with dark brown blisters. The first side should have charred spots before you flip.

While naan cooks, mix melted butter with minced garlic. Brush generously over hot naan straight from the skillet, then sprinkle with cilantro if using. Stack on a plate and cover with a towel to keep warm.