Chipotle Mexican Grill Inc. plans to hire 4,000 employees in a single day next month, seeking to counter a tightening market for restaurant labor by dangling the possibility that high-performing recruits could someday earn six-figure salaries and stock in the burrito chain.

The planned Sept. 9 hiring binge -- which would expand Chipotle’s 59,000-member workforce by nearly 7% -- is one of the starkest examples yet of restaurant chains stepping up recruitment efforts as the industry struggles to attract and retain employees. A stronger economy, rising demand for restaurant meals and a string of minimum-wage increases imposed by cities and states have shrunk the pool of available workers.