Combine yeast, water, and oil in a small bowl; let stand 5 minutes.
Combine flour and salt in a large bowl, and make a well in center of mixture. Stir in yeast mixture and nigella seeds.
Turn dough out onto a lightly floured surface; knead dough until smooth and elastic. Place dough in a greased bowl, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 1 hour.
Divide dough into 20 equal pieces, and shape into very thin rounds. Let dough rest 10 minutes.
Heat a large heavy skillet over medium-high heat. Add flatbreads, one at a time; cook until blistered and puffed. Turn flatbreads over; cook 1 more minute. Remove and cover to keep warm and pliable. Serve immediately.