This is definitely on the top ten list of my all-time favorite dishes. Aside from the uniquely rich yet delicate flavor of milkfish, I just love how the lemony hint of ginger, the pungency of garlic, the subtle heat of jalapenos, and the natural sweetness of pineapples come down together into a beautiful syrupy glaze that just makes the fish taste so much fresher.
The flavors in this poaching liquid just work so well together that it does work for a lot of other options aside from milkfish. I've tried it with mackerel, tuna, swordfish. . . a lot more, really. In fact, it works well with pork and chicken too.
Start with a good size of milkfish. Milkfish is a relatively bony fish so getting a good size will give you a better bone to flesh ratio. Honestly, I really don't mind this structure because I find the taste of milkfish really rewarding despite all the hassles of picking out those bones.
Most of you may want an easier meal and wish to use a fleshier fish. Go ahead. Try this with jack, mackerel, tuna, or milkfish fillets which should not that be too hard to find. You can find troncons, or butterflied cuts of milkfish, deboned, in the frozen fish section of most grocery stores.
Get the garlic and ginger into a fine mince to get the most out of their flavor. You may chop those chilis too but leaving them whole gives you a wonderful peppery flavor without too much of the heat. Finally, go for whole to slightly cracked black peppercorns so you can easily pick them out of the glaze later. You'll want that pungent flavor and aroma from them but you wouldn't want tiny specks of pepper ruining that syrupy glaze in the end.
Here's a tip for keeping that glaze spotless for serving: get all those aromatics in a spice sachet or a tied-up coffee filter that you can easily pick out right at the end of cooking.
Get all those aromatics at the bottom of the pot together with the chunks of pineapple, pineapple juice, and white vinegar. This layer of ingredients shall serve as a bed that'll keep the skin of the milkfish from sticking to your pot.
Don't pour in any other liquid yet, not until you get the fish in. Arrange the fish on top of the aromatics then pour in just enough water until the level of liquid in your pot reaches half the height of the fish. Doing so will keep your fish poaching instead of boiling, which is a rather harsh cooking method that could easily break its flesh. ==> My Current Favorite Slow Cooker
Leave your pot for about 4-5 hours on a low heat setting and the milkfish should come out perfectly moist and tender but still firm.
Depending on the amount of liquid that you've used, you may need to take that poaching liquid to reduce further over the stove. It'll be good to dig in straight out of the pot, but allowing those natural pineapple sugars thicken into a thin syrup will be so much more rewarding.
Finally, adjust for seasoning with some salt, or much better, some good Thai fish sauce.