D&D 5E (2014) Next adventure after Lost Mines?

[Eyes of Nine]

Can we break strahd down to a short adventure for 5 to 6/7th level? Or is it more like once you start Strahd, you should finish it?

 

[Eyes of Nine]

The MT Black collection looks promising.

 

[Enrico Poli1]

Can we break strahd down to a short adventure for 5 to 6/7th level? Or is it more like once you start Strahd, you should finish it?

No you can't. You can only skip the first portion and start at level 5.
But CoS is by far the best of your options.
I hope your DM will be able to handle it.

 

[Charlaquin]

I think Forge of Fury would be a great follow-up to Phandelver. Place Khundrukar in the mountains near Phandelver and have Dugeddin’s Clan be part of the Phandelver’s Pact. Now that Wave Eccho Cave has been rediscovered, the Rockseekers are keen to take back Khundrukar and get the whole operation up and running again. It fits right in with the story, it’s a straightforward dungeon delve so it should be easy enough to run, and it’s in the right level range.

 

[Swarmkeeper]

I agree that CoS is probably too complex for a new-DM.

If you haven't dipped your toe in the Ghosts of Saltmarsh waters, your friend might try either of these chapters (each adventure chapter in GoS can really stand on its own):

Salvage Operation (intended for 4-6 PCs starting at 4th level)
Isle of the Abbey (intended for 4-6 PCs starting at 5th level)

The Prepared! and Prepared! 2 collections from Kobold Press both contain simple yet detailed one-shots that a new DM can cut their teeth on.

For more non-WotC level appropriate stuff, this site is a great resource.

 

[aco175]

I made these Southcrypt modules for my home group to play directly after LMoP. It may work good for a new DM since all the stats are given and it it is laid out in bite-sized chunks with smaller mini-adventures. Plus, you may not have read them.

Southcrypt Pass
Southcrypt Falls
Southcrypt; The Upper Halls