Happy Lamb Hot Pot, the Inner Mongolian-style restaurant at 215 S. Ellsworth Ave., is marking 20 years in downtown San Mateo with a $20 coupon for Downtown San Mateo Association members.

The deal has conditions. Diners must spend at least $100 (excluding alcohol, taxes, gratuity, lunch specials and combo meals), and the coupon cannot be combined with other discounts. One coupon per table per visit.

To redeem, diners visit the restaurant, ask staff for the reward and provide their registered DSMA mobile number when ordering. Each coupon is valid for 30 days from the date claimed.

The DSMA posted the promotion on its events calendar, calling the coupon a thank-you for members.

The San Mateo location is independently owned and operated under a license from Happy Lamb Investment International, Ltd. Business records show the restaurant opened in 2006 at the Ellsworth Avenue address, one of nine California locations listed on the brand's website.