Add all ingredients into a grinder and blend till you get a grainy consistency
Do not grind to a very smooth paste because the texture this consistency will lend to the fish, will hit the right spot on your palate. A finer texture I think would work better for meat
Though this spice rub is suitable for freezing, since it contains garlic and fried onion, I would not advise keeping in the freezer for over 10-15 days
If you make a small batch and little remains, try adding into your curry for a lift in flavour
If you do not deal well with spicy red chilli flavours, then rule out the whole round red chilli completely and instead add a small pinch of paprika just for a hint of flavour