Fish Steaks and Avocado with Tomatoes, Lime, Chilli and Angostura Bitters

I created this recipe from the memory of a dish I once tasted in Trinidad. There I also learnt how much Angostura bitters (whose recipe is still kept secret, locked in a bank) can enhance both savoury and sweet dishes. You can use any white fish that produces good steaks, such as cod or swordfish. A Trinidadian told me that marinating fish in milk makes it more tender.