The following is shamelessly stolen from http://bewitchingkitchen.com/ , adapted where I felt like it.
1/2 tsp instant dry yeast
150 g pitted green olives, minced
25 g olive oil
1 tsp salt
550 g bread flour
1 medium onion, finely chopped
1 Tbs poppy seeds
Combine water, yeast, olives, salt, and olive oil in a large bowl. Mix in bread flour, then knead briefly. Cover and place in the refrigerator in an oiled bowl, and let rise for 1-2 days.
Turn out dough onto a floured surface and divide into 10 even pieces. Shape into balls and let sit for one hour. Preheat oven to 450˚F. Fry onion over low heat without oil until soft, then combine with poppy seeds.
Take five of the balls and stretch a dent in each so there is but a thin screen of dough in the middle. Fill with onion and poppy seed. Place on parchment paper on a baking sheet, and cook for 15-18 minutes. Repeat with remaining 5 balls.