We caught up with the rapper this weekend at BOA Steakhouse ... where he told us about his progress and how he plans to stay on track in the future.

Xan says, he is 40 days clean, after doing 30 days in a detox center and 30 days in a rehab facility. He tells us he's feeling better than ever, and blessed to finally be sober.

One element of his sobriety will be controversial to some people -- Xan says his rehab facility allowed patients to smoke weed, which he says helped him. That approach has been called "California sober," something Demi Lovato said worked for them ... until it didn't.

For now, LX is in great spirits and even showed off his GF while opening up to us about his new lifestyle. He's also looking forward to going on tour May 25 -- but, he's gonna be extra careful this time ... planning to bring a sober companion to make sure everything goes well and he isn't tempted to relapse.

As we've previously reported, Xan checked himself into a hospital in March and got 51/50'd  ... he said he was experiencing a mixture of exhaustion, dehydration and depression from things he was seeing online.

He ended up spending 3 days in the psychiatric ward before getting the green light to check into a part of a facility focused on mental health.