Preheat the oven to 375° F and position a rack in the center.
In a lidded heavy-bottomed pot, preferably a Dutch oven or other cast-iron vessel, add the chickpeas, potatoes, garlic and seasonings. Stir to combine and bake covered for 25 minutes. Uncover the pot, stir, and return to the oven for another 10-15 minutes, until the top is crisp and golden brown.
While the chickpeas bake, make the cucumber yogurt. Wrap the cucumber in a few paper towels and squeeze out any excess moisture. In a bowl, stir together the ingredients. Add salt to taste.
Serve the chickpeas and potatoes over the cucumber yogurt with warm flatbread. Garnish with more fresh dill and a drizzle of olive oil.
