Step 1: Start by preparing the hung yogurt, if you haven't already. Take regular yogurt and place it in a muslin cloth or cheesecloth over a bowl. Tie the ends and let it hang for a few hours or overnight in the refrigerator until most of the whey has drained out and the yogurt has a thick, creamy consistency.

Step 2: In a large bowl, add the drained and rinsed chickpeas. Using a fork or a potato masher, begin to smash the chickpeas until most are mashed but some chunks remain for texture.

Step 3: To the mashed chickpeas, add the hung yogurt, hot chili sauce, balsamic vinegar reduction, red chilli flakes, and dried oregano.

Step 4: Season with salt and pepper to your preference. Mix all the ingredients until they are well combined. The resulting mix should be creamy with chunks of smashed chickpeas.

Step 5: Take a slice of whole grain bread and generously spread the chickpeas and yogurt mixture onto it.

Step 6: If you prefer, add a layer of fresh lettuce, a slice of tomato, and cucumber for added freshness and crunch.

Step 7: Cover with another slice of bread to complete the sandwich. Repeat with the remaining bread and mixture.

Step 8: Cut your sandwich into halves or quarters as you prefer and enjoy!