Substitution for green meat radish

Escallion = scallion = green onion.

I think it's possible to substitute regular onions in some situations, but there are a lot of variables.

First off, scallions have a sharper, more grassy flavor than onions, though they're not as strong.

Then there's the question of which kind of onion you want to substitute. White onions have some of that same sharp flavor, and are quite strong. Yellow onions are much milder and sweeter, and might not be such a close flavor match. Red onions are somewhere in between, in my experience. I would probably try white onion, but in much smaller quantity than called for of scallions.

It's also important to consider how the scallions are being used. If they're being cooked into the recipe, that's very different than if they're being added right at the end, or even as a garnish. I think the substitution is less of an issue if the scallions are to be cooked. If they're to be more or less raw, I'd suggest white onion, not too much of it, and sliced very very thinly, as a raw white onion is really strong.

Whatever you try, bear in mind that it won't be exactly the same. But that certainly doesn't mean it'll be bad--just different.

Scottish,

Use equal amounts of ginger to substitute for galangal. And yes, it is the best substitute available from your average non-Asian grocery store.

If you can get your hands on dried, powdered galangal, however, you can do better. Add about half the amount of ginger, and around midway through cooking add a teaspoon of powdered galangal for every tablespoon of fresh in the recipe. The combination of fresh ginger and powdered galangal will be very close to fresh galangal in flavor.

Also, if you make a field trip to an Asian market, peeled galangal cut into chunks freezes quite well.