Place 2 cups flour in a large bowl and make a well in the center. Break the egg into it, add the salt and a little water at a time. Bring the dough together, kneading well and adding more flour or water as necessary. Cover the dough with a bowl or towel. You’re aiming for soft dough. Let it rest 20 minutes. Meanwhile, make the filling.
For the pierogies
Boil potatoes in salted water until fork tender. Meanwhile, brown lamb. Drain potatoes, then mash in a large bowl, adding the Greek yogurt to make smooth. Drain lamb and add to potatoes. Add seasoning, stirring to combine. Taste and adjust if necessary.
On a floured work surface, roll the dough out to about 1/8-inch and cut with a 2-inch round. Spoon a portion (no more than a teaspoon) of the filling into the middle of each circle. Fold dough in half and pinch edges together. Gather scraps, re-roll and fill. Repeat with remaining dough.
Bring a large pan of salted water to boil. Boil the pierogies about five at a time, in order to let them have room to move around. When the pierogi rise to the surface, continue to simmer for about five minutes.
Serve immediately, or let cool and then fry in a small amount of oil. Serve pierogies with cucumber raita, below.
For the cucumber raita
Peel cucumber if desired. Halve it, scoop out the seeds, and chop finely. Let rest in a fine sieve over a bowl to drain while you peel and dice the garlic. Mix all ingredients together and set aside to let flavors mingle while frying pierogies.