It’s Friday night on a busy street corner in Los Angeles’s Koreatown, and Denise Vallejo showers a handful of cilantro over a flour tortilla piled high with grilled seitan and her signature melty cassava-flour-and-cashew cheese. Her “Chicali” taco, a vegan version of the carne asada tacos sold across Mexicali, a city in northern Mexico where Vallejo’s family is from, costs $7, on the higher side for the neighborhood.