Add yogurt to a large piece of cheesecloth, and place over a colander set inside a bowl for about 30-45 minutes. Keep refrigerated while it’s draining. This ensures a thicker sauce. *if you don't have a cheesecloth, add the yogurt to a fine mesh sieve*
Add minced cucumbers to a mesh sieve placed over a bowl, and sprinkle with 1 tsp of the salt. Stir and let sit for 30 minutes.
Fold a paper towel in half and press down gently but fairly firmly on the cucumbers, to get out as much liquid as possible. This ensures you don’t have a watered down sauce.
To a mixing bowl, add yogurt, cucumbers, garlic, lemon juice, lemon zest, dill, olive oil, black pepper and remaining 1/2 tsp salt. Stir well to combine.
Cover and refrigerate for at least 1 hour, but sauce will keep for about 4 days.
While the sauce is chilling, slice each slice of pita bread into 6 triangles. Arrange on a baking sheet. Preheat oven to 350°F. Brush each triangle lightly with olive oil and sprinkle with sumac and oregano to taste.
Bake for 6-8 minutes, until pita is crisp at the edges.