This is a nod to the popularity of Japanese food, in particular sushi, in Mexico City. Here, tuna steaks are seared with a sesame seed crust and served with a wasabi mayonnaise, chopped scallions, and cilantro or the more exotic radish sprouts. Flour tortillas are used because they are a more neutral background to the tuna.
Make the mayonnaise
Stir together all ingredients and taste to check seasoning.
Prepare the tuna
Pat the tuna dry with paper towels and season with the salt.
Put the sesame seeds on a plate and press both flat sides of the tuna steaks onto seeds to coat.
Heat a large, heavy skillet over medium-high heat until hot, about 2 minutes. Add the oil and swirl the pan to distribute, then add the tuna steaks, in batches if necessary, and sear for about 2 minutes a side, until just the outside 1⁄4 inch is cooked but the center is still translucent.
Transfer the tuna steaks to a cutting board and slice. Make the tacos with the wasabi mayonnaise, avocado, scallions and sprouts
Photo: Romulo Yanes