When asked about the best Strip Mexican food in Vegas, I’ve been quick to recommend our version of Border Grill at Mandalay Bay. But I recently returned to another favorite, the vibrant pink and orange eatery hiding in the less-than-accessible culinary corridor at MGM Grand, and now I’m convinced it’s at least a close second.

I’ve always loved the space at Diego, several different rooms with brash colors and almost avant-garde decor. It’s a great jump-off spot for snacks and cocktails, with terrific margaritas and sangria, a trio of fresh, flavorful table salsas, and fun small plates like braised beef taquitos or queso fundido with poblano chiles.

But the real food is real good, seemingly improved in the year and a half since Christina Olivarez took over as executive chef. She started as a cook at Fiamma, moved over to Diego as sous chef and is now running the show. Several dishes have been added under her tenure, and the end result is a Mexican restaurant that should be moved out of the “maybe overlooked” category and into “serious contender” status.

First, Olivarez and her crew are maintaining stuff that has always been great. The guacamole is prepared tableside and made unique with sun-dried tomatoes and onions soaked slightly in vinegar to cut their bite and balance things out. It’s subtle, smooth and delicious. The can’t-miss dish is pit-style barbacoa goat, a pile of rich—but not gamey—shredded meat served with warm corn tortillas, the ultimate shared taco plate with some of that guac or those salsas.

More balance: The lighter side features roasted tomato and chipotle soup with lentils and grilled avocado, or a nice selection of seafood cocktails and ceviches. Traditional, familiar plates like chile relleno, cheese enchiladas and carne asada (though the latter is upgraded from skirt steak to ribeye) will satisfy the less adventurous. New signature stunners include a rightfully complex chicken mole and the dueto de carne con huitlacoche, comprising braised beef cheek and a lovely, rare filet mignon with nopales, chiles and different versions of the funky, rich corn fungus. It’s quite the dish, demonstrating that this kitchen is on the attack. I’m impressed; time to visit Border Grill to see if they’re keeping up.