The outdoor strip mall has become a hot commodity.Allen J. Schaben/Los Angeles Times via Getty ImagesInvestors are seeing new value in the strip mall.A lack of supply and an uptick in in-person neighborhood shopping has increased their value.One commercial real estate investor called the opportunity a "retail renaissance."Strip malls, of all things, appear to be trending up.After decades of decline brought on by the rise of large box stores, e-commerce, and the pandemic, the humble and sometimes derided neighborhood shopping center had long been on the outs.