In a small bowl, separate the layers of the sliced onion.
Add the salt, coarsely cracked peppercorns, red wine vinegar, and paprika to the bowl.
Stir well to combine, ensuring the onions are fully coated.
Let the mixture sit at room temperature for at least one hour to allow the onions to soften and pickle.
Just before serving, stir in the optional cayenne and/or chaat masala if using.
Taste and adjust seasoning as needed.
Adjust the resting time. For a crispier texture, let it sit for just 30 minutes. For a softer, more pickled flavor, let it marinate for a few hours or even overnight in the fridge.
Don't be shy with the chaat masala! This tangy Indian spice blend adds an incredible, complex layer of flavor that takes the chutney to the next level.