Sift the flour together with the salt into a bowl and mix in the yogurt. Warm the milk slightly and stir in the sugar and the yeast. Add to the dough and continue to mix. Add a little water or flour as necessary, to get the dough to the correct hard consistency. Knead well for at least 15 minutes. Return to the bowl and cover with a damp tea towel. Put in a warm place to prove for 4-5 hours. The dough should rise to twice its original size. To cook the naan, Put off lumps of dough approximately 5-8 cm/2-3 inches across and, using a combination of rolling and pulling, form into elongated shapes. Put the poppy seeds into a saucer, wet the hands with a little water, pick up a few poppy seeds on your wet hands and press them into the top of the naan. Lay each naan out on a baking tray, brush with a little of the melted ghee or butter and bake in a pre-heated hot oven, 230ºC/450ºF/Gas Mark 8, for about 10 minutes until the naan puff up and turn golden brown. Serve immediately, keeping the naan warm in a cloth.