Use Romex, not Puppet Stayman

A popular convention after 2NT openings is Puppet Stayman, because it's easy and it finds 5-3 Major fits. The 3♣ bid is used to ask for 4 or 5 card Majors, and you won't miss a 5-3 or 4-4 fit (except when responder has a 5 card and opener has 3 card support, but in this case responder will usually bid something else, like transfer).

There are however hands which become problematic because of this convention: 5♠ and 4♥ for example. Using regular Stayman, you can use Smolen (2NT-3♣-3♦-3M) to show a 4 card M and a 5 card OM, but this isn't possible anymore when using Puppet Stayman.

So how do you solve this? There are many ways:
- use the 3♠ bid for such hands. It's quite a waste however. Since 2NT is a huge preempt for your own partnership, you better keep as much space available as possible for slam investigation.
- use 3NT for such hands. Problem here is that it's not forcing, so when you have slam interest you have a new problem. And ofcourse you can't bid 2NT-3NT, so the defense will have more information available.
- treat it as 4-4, or transfer and just ignore the 4 card suit. Problems are obvious: you usually miss the fit in the suit you ignore.
- use Romex instead of Puppet Stayman. This is my preferred method, since it keeps 3♠ and 3NT bids free to show various types of hands.
- there probably are a lot more solutions...

Some of you might wonder what Romex is exactly. It basically combines the merrits of Puppet Stayman with the possibility to show 5♠ and 4♥. All it requires is a different response structure after 3♣:
3♦ = <4♥, <5♠
3♥ = 4-5♥, <4♠
3♠ = 2-3♥, 5♠
3NT = 4-4 in the Majors

- After 3♠ and 3NT responder knows enough.
- After a 3♥ response you can use 3♠ to search for a 5 card ♥ (opener bids 3NT with 4♥ and cuebids with 5♥s)
- After a 3♦ response, you can search for a ♠ fit using 3♥, and you can show that precious 5♠-4♥ hand with 3♠.

It's a bit more complicated, but it gets the job done. You can even save space for cuebidding in a lot of situations where the fit is obvious:
2NT-3♣-3♦-3♠-4♣+ cues with ♠ fit (♥ fit is impossible)
2NT-3♣-3♥-3♠-4♣+ cues with ♥ fit (shows 5♥)
2NT-3♣-3♠-4♣+ cues with fit (this is an agreement, can be used for other purposes however)
2NT-3♣-3NT-4♣ sets ♥, start cuebids
2NT-3♣-3NT-4♦ sets ♠, start cuebids

Around half of the worldclass players use regular Stayman for various reasons, and the other half of them uses some kind of (modified) Puppet Stayman. What's best? I have no idea, and apparently even the topplayers don't agree on this matter.