Stir together the yeast, warm water and sugar until yeast is dissolved and set aside. Add flour and salt to a large bowl and add in the yeast mixture. Stir until combined and a slightly sticky dough is formed. Knead until dough is elastic and smooth, about 5 minutes, adding more flour if it’s too sticky. Cover and let rise for 15 minutes.

Combine 1 cup of the Greek yogurt with lemon zest and garlic and season with salt. Add the chicken thighs and coat completely. Thread onto skewers and set aside.

Heat a cast-iron pan over high heat. When pan is hot, add the cucumbers and cook, tossing, until lightly charred in places, 4 to 6 minutes. Remove from the heat. Add a drizzle of olive oil to the pan and add the skewers and cook until golden brown and cooked through, about 5 minutes per side.

While chicken cooks, add remaining 1 cup Greek yogurt to a blender. Add the feta and the olive oil and blend until whipped and smooth.

Wipe out skillet and lower heat to medium. Lightly dust a flat surface with flour. Divide the dough into 6 pieces. Roll each piece out to an 8-inch circle. Place in the hot pan and cook until golden brown, about 1 minute per side. Repeat with remaining dough.

Spread 1 piece of the flatbread with the feta-yogurt mixture. Top with the chicken and cucumbers.