When Wallash met Jay Goodwin, they were students at the University of California, Santa Barbara. "Jay became my best friend, and we started homebrewing together our senior year," Wallash recalls. "I was studying molecular biology and realized that brewing uses the science of biology to make art in the form of beer."

After graduation, Goodwin went to work at The Bruery in Orange County. The duo quickly came to the realization that their favorite style of beer was sour. "Back then, it was really hard to find sour beer though because there wasn't a whole lot of it out there," Wallash adds. Fortunately, Goodwin was learning how to make it.

"We decided to start an all-sour brewery," Wallash says. "Sour beer is what we love, and we felt that if we focused entirely on sour beer, we'd learn more about it and be able to make a better product."

The Rare Barrel's reputation among craft beer enthusiasts and competition judges indicate that's exactly what the founders, which include Brad Goodwin, Jay's father, have done. The Rare Barrel's awards include silver and bronze medals at 2018 Festival of Wood and Barrel-Aged Beer, bronze at 2018 World Beer Cup, and silver and bronze at 2015 Great American Beer Festival.

At The Rare Barrel's tasting room and kitchen in Berkeley, guests will usually find five to 10 of the brewery's sours on tap as well as four to six non-sour guest beers and two wines. "Last year, we made around 70 different blends," Wallash says. "About 40 were different brands in bottles and another 30 were brands on draft only."

The brands ranged "anywhere from a blend of golden sours, to a dark sour with raspberries, to a golden sour with nectarines, to a 3.5 percent ABV grisette with really light acidity," Wallash explains. "We like to explore the spectrum of flavors you can create with different malts, different fermentation profiles, yeast, bacteria, and different acid levels in the beers as well as different types of fruits and spices."

All of The Rare Barrel's beers are aged in oak for an average of nine to 12 months. "Around 90 percent of the barrels we use housed red wine for about five years," Wallash says. "The idea is that the tannins from those barrels have mostly been stripped to make the red wine, but there are still some tannins left to give a nice oak accent -- but not too much oak character -- to the beer."

Wallash and Goodwin have also been experimenting with aging in bourbon, tequila and gin barrels as well as freshly emptied wine barrels. "Things like that can definitely add character as well," he adds. "Barrels are fun ingredients to play with."

Beer-wine hybrids are a fairly new style for The Rare Barrel, and Wallash said their popularity is rapidly increasing. "We've been working for the last two years to make sour beers fermented with grapes," he explains. "These beer-wine hybrids showcase the similarities between sour beer and wine. They have similar acidities and are usually not bitter or sweet. They generally have some sort of tannic and barrel-aged character and some of the complexities you find in a really nice wine."

A recent release in this vein is Blurred Sb, a hybrid made with sauvignon blanc grapes that blurs the lines between beer and wine. "I'm really excited about this beer because it's the first beer-wine hybrid that we've made using sauvignon blanc grapes," Wallash adds. "In general, those are amazing, bright grapes."

Favorite beers: "Alvarado Street Brewery's Yeast of Eden has an amazing grisette called Family Miner," Wallash says. "It's a low ABV beer with light acidity and a really amazing saison fermentation profile. That's a beer I'm really loving right now. I also like everything Cellar Maker Brewing in San Francisco puts out. Moonraker Brewing is also doing some really good stuff, and whenever I can try Societe Brewing's beer, from down in San Diego, I love it."

Challenges: Though Wallash says that he knows The Rare Barrel released under 1,000 barrels of beer last year, he doesn't know exactly what was brewed versus what was packed because "we end up making a lot more wort than we end up packaging." The Rare Barrel's commitment to quality has led the team to dump about 30 percent of the beer they've fermented since starting the brewery.

"That's higher than we thought it would be," Wallash adds. "We expected somewhere around five percent because we heard that is an industry standard. We planned on dumping 10 percent to make sure we were focusing on quality first. But Jay is very adamant about only blending in the good barrels and not blending in bad barrels just to hide off flavors. If there's an off flavor in a barrel, he dumps it down the drain. We take that barrel out of rotation, too."

Opportunities: Wallash says that The Rare Barrel's biggest opportunity right now is sour IPAs. "We've been making a hazy IPA and then blending in a small portion of our barrel-aged sour beer," he explains. "The idea is that you have this bright, tropical, juicy IPA but instead of having a light bitterness, it has a light acidity that's somewhere around the acidity you'd find in a glass of orange juice."

Wallash says the team has spent five years exploring how to integrate hops and sour beer successfully. "Most breweries use hops on an everyday basis," he says. "But hops added on the brewing side prevent the beer from becoming sour, and we want to encourage our beers to go sour. It's been a fun adventure to get to this point where we can make an IPA and blend it with our sour."

He notes that The Rare Barrel is canning rather than bottling the sour IPA to encourage consumers to drink it fresh. "Our customers rightly believe that they can drink our beers now or cellar and drink them later like a wine," Wallash adds. "From our QC testing, we've found that the very first batch of beer we ever made and packaged back in December 2013 still tastes great. But with the sour IPA, we want people to drink it within a couple weeks of purchase. That's why we're putting it in cans."

Needs: "We're in a good place," Wallash says. "But it's always great to sell more beer directly so you can generate more revenue to increase wages and provide more for your staff. We're always working to do that. It would also be nice to buy our own canning line, but those are expensive."