Hamachi crudo and its endless, perfunctory variations blur together, but the rendering at Mirra, in Chicago, is a striking thunderbolt of flavor: slices of yellowtail drenched in lime-spiked buttermilk, hot and tangy with a garlic and serrano achar, tucked under a delicate crunch of nopales, ginger and curry leaves.

In one bite, the fresh and drinkable buttermilk, called chaas in Hindi, is invited to party with Sinaloan aguachile, bringing together flavors from India and Mexico into something new, delicious and essentially stateless.

“Is it Indian? Is it Mexican?” Rishi Kumar said on the phone. “No, it’s something else.”

Mr. Kumar and the co-chef Zubair Mohajir opened their restaurant last year in the Bucktown neighborhood, and quickly found the house packed for their energetic and sharply intelligent Mexican Indian cooking.

The co-chefs Rishi Kumar and Zubair Mohajir opened their bustling Chicago restaurant, Mirra, last summer.Credit…Daija Guy for The New York Times

It’s not unusual to see margaritas crowding tables in the late afternoon as diners share quesadillas shining with melted Amul cheese and rip pastry off their lamb barbacoa biryani. Like the more successful dishes on the menu, the biryani surfaces regional ingredients and techniques without veering toward the formulaic.

Mexican Indian food might sound like a bit of a novelty, orchestrated for a fast-food chain’s viral marketing campaign — it’s not.