Steven Van Zandt is smiling. He's between gigs, on a respite from performing on his longtime pal Bruce Springsteen's European tour and, at this moment, happily anchored to a poolside chaise lounge – sunscreen slathered, hat askew – at Barcelona's Hotel Arts in Spain.

"It's nice to get a break," he says.

Van Zandt may be the picture of stationary bliss at the moment, but as an artist he is virtually impossible to pin down.

Consider that his last name is Dutch, but he's actually Italian, Malafronte was the surname before his mother remarried. He's a musician, sure, a longtime member of Springsteen's E Street Band, but also a political agitator whose efforts helped lead to the freeing of Nelson Mandela. He's a man who insists he doesn't like the spotlight, and yet he made a household name for himself as a first-time actor playing Silvio Dante in "The Sopranos."

All of that, plus his exploits as a songwriter, producer, radio show host, rock music educator and pirate-fashion pioneer, help explain why Bill Teck's new HBO documentary, "Stevie Van Zandt: Disciple" (airing on HBO at 8 p.m. ET June 22 and streaming on Max), is 147 minutes long. It could have been longer.

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"I could do a second doc, too," Teck says with a laugh. "If you’re a fan, there are many Stevies to cover. There’s Miami Steve, Little Steven, Frank the Fixer and Silvio Dante. And then you gotta explain that Silvio Dante helped free Nelson Mandela. It’s a lot."

Among the highlights of Teck's "Disciple" doc:

Who is Southside Johnny and what does he have to do with Steven Van Zandt?

Bruce Springsteen and Stevie Van Zandt both had rocking bands as teenagers roaming the various clubs on the New Jersey shore in the late '60s. Their friendship has never wavered even though Van Zandt left his buddy's side for about a decade starting in 1984.

But Van Zandt's earliest success was actually writing songs for and performing with another Jersey Shore legend, Southside Johnny Lyon, whose 1970s hits with Southside Johnny & the Asbury Jukes included Van Zandt's "I Don't Wanna Go Home." For fans who only know Van Zandt as the Boss's faithful "consigliere," the new doc provides insights into just how hard Van Zandt worked to learn the craft of writing timeless rock songs.

"Bill spent a good amount of time on that early era, and he was right to do that," says Van Zandt. "People sort of know about the origins of that Jersey thing, but they don’t know all the details."

What is Steven Van Zandt most proud of?

In "Disciple," Van Zandt explains that a trip to South Africa in the '80s, one partly inspired by Peter Gabriel's song "Biko" about slain African civil rights leader Stephen Biko, opened his eyes to the need to lend his voice to the struggle.

His celeb-packed 1985 song and video "Sun City" challenged Western musicians to turn down invitations from South Africa's apartheid regime to play lucrative gigs at the resort while Black Africans living nearby had no rights. The ensuing personal and corporate boycotts eventually created such financial havoc that it – along with other efforts – forced a regime change that included the freeing of future South African president, Nelson Mandela.

"In terms of what I am most proud of in my life, I'd say the most obvious thing was the work in South Africa," he says. "It was a wonderful moment, to realize an actual victory. When you’re in international liberation politics, you don’t have clear victories, you move ahead one inch here then get knocked back. But this was a rare clearcut and complete victory."

Why did Stevie Van Zandt leave the E Street Band in order to go solo as a musician with a political agenda?

In "Disciple," Springsteen says on camera that in their early days together, Van Zandt didn't want to mix music with politics. But when that sentiment changed, "he went all in." Eventually, his activism would also include Native American rights issues.

So where did that sense of righteous indignation come from? "I don’t know really," says Van Zandt. But then he thinks about it, and the answers come easily, rooted, as it is in many cases, in childhood.

"I suppose there were series of circumstances that must have played upon my natural instinct for justice, and recognizing injustice, and being uncomfortable with injustice," he says. "I always hated bullies really. I was bullied as a kid in high school, maybe it starts there, I don't know. Early on in my career, I really didn’t have any ambition, I had no desire to be in the spotlight, I still don’t. But when I went solo I started reading these books, and I decided my identity would be talking about politics."

Stevie Van Zandt was sure home movies of his 1982 wedding were lost until an HBO producer found the videocassette

One revelatory scene in "Disciple" showcases Van Zandt's 1982 wedding to his wife, actress Maureen Santoro. Bruce Springsteen is the best man, and none other than Little Richard is the presiding official. Percy Sledge is belting out his 1966 hit "When A Man Loves A Woman."

"And I'm pretty sure (blues ace) Little Milton was there as well, somewhere," says Teck, as Van Zandt just nods at the memory. But the footage was considered lost. But an intrepid producer on the documentary dug through countless plastic containers and eventually found the videocassette of those nuptials.

"It was way in the back of this warehouse, like where they put the ark at the end of 'Raiders of the Lost Ark,'" says Teck. "We found footage of Stevie and Nelson Mandela, too, which Stevie didn’t have. So there are these rock treasures that would have been lost. It is a trip to present them to the world."

Why Paul McCartney's compliment made Stevie Van Zandt twist and shout

As Teck was assembling his documentary, Van Zandt, ever busy, only saw little snippets. Two such snippets were all the musician had to see to know he had lived his life right.

One features Paul McCartney explaining that while he considers himself knowledgeable about rock 'n' roll and its history, "this guy knows more." And the other is a tribute from Mike Stoller, he of the fabled hit-making duo Leiber and Stoller, complimenting Van Zandt's songwriting.

"When Bill showed me that, I was like I don’t care what else is in this movie," he says, laughing. "I told him, the rest of the movie can be a Bugs Bunny cartoon for all I care. I got Paul McCartney and Mike Stoller giving me compliments? Forget about it, unbelievable."