In a large mixing bowl, combine the flour, salt, and yeast. Incorporate the softened butter and Greek yogurt, then gradually add the water until a soft, slightly sticky dough forms.
Knead the dough on a floured surface for 5-10 minutes until it is smooth and elastic.
Place the dough in a lightly oiled bowl, cover, and let rise until it has doubled in size, about 2 hours.
Punch down the dough and divide it into six equal parts. Roll each piece into a 4.5-5 inch diameter circle.
Let the circles relax on a lined baking tray for 30-45 minutes.
Combine the melted butter, garlic puree, and chopped coriander in a bowl.
Heat olive oil in a frying pan over medium-high heat and fry each flatbread for 3-4 minutes on each side until golden and puffed.
Brush the hot flatbreads with the garlic-coriander butter mixture before serving.