Remove the fish from the refrigerator.
Heat the remaining 2 tablespoons of oil in a high-rimmed skillet or frying pan over medium-high heat.
Remove each piece of fish from the bowl, ensuring it is nicely coated with the marinade.
Place in the hot oil one at a time. Do not overcrowd. You can fix it in batches.
Save any remaining leftover marinade and add the onions to them. There should be very little marinade but enough for a light coating. You can even use them without the marinade.
Fry the fish on each side for 3-4 minutes until golden.
Place the fried fish on a paper towel to drain.
Add the sliced marinated onions to the hot pan. There should be enough oil to lightly sauté the onions until they are translucent. Drain on a paper towel.
Serve fish on a platter.
Sprinkle some chaat masala over the fish (optional).
Garnish with the sautéed onions. You can also use raw onions or garnish with lemon slices and cilantro. Any chutney will pair well with it.
Serve with naan or any kind of flat bread. It goes well with a rice pilaf.