People have covered this method, so i doubt this will be new information. I've only recruited Minthy twice (I kill her more often than not, even in my evil runs), so I'm not an expert, but this is how I got her in my good runs:
- kill Gut off in her side room, you should always take her out first, doing her later seems to cause issues?
- free Halsin, but don't have him with you.
- then put the grove in it's raid state. You can do this either by letting Sazza tell Minthara where it is, or just doing so yourself, then agreeing to raid the grove.
- (Optional: kill Dror Ragzlin after Minthara runs off to prepare for the raid. You can kill the entire camp after Minthara runs off and it shouldn't affect the raid.)
- don't worry about Halsin, he takes care of himself. He'll show up in the after-raid cutscene looking like a proud dad.
- Get back to the grove and then when Minthara orders you to open the gate, you don't, so she is hostile to you and the raid begins.
- KNOCK HER OUT, DO NOT KILL HER. Just get some people to leap over to where she's stationed and go ham until she's unconscious. I parked barrels at the base of her rock before the raid and blew the rest of her army the fuck up so i didn't have to worry about them. loot her if you want, I haven't had her lack of clothes cause any issues.
- play your game as normal. Maybe speed your way to Moonrise if you feel insecure about it.
After a long rest, Minthara should have vanished and you can find her being dressed down at Moonrise, you then have to rescue her from the prison and take her outside Moonrise, then tell her to go to your camp in the dialogue that follows. Go from the prisons through the side exit to the docks and jump over to the mainland, it's the easiest path with the least amount of enemies, i've found. i have used this method successfully in the last few weeks, so unless update 23 broke this too, it should still work.