How to Make It
Whisk together chicken stock and cornstarch in a small bowl. Set aside.
Melt lard in a medium saucepan over medium-high. Add finely chopped yellow onion; cook, stirring occasionally, until translucent, 3 to 4 minutes. Stir in finely chopped tomato, dried oregano, ground cumin, smoked paprika, granulated sugar, and finely chopped garlic. Cook, stirring occasionally, 2 minutes. Add chopped roasted Hatch green chiles, kosher salt, and fresh lime juice.
Bring to a boil, keeping heat at medium-high. Add cornstarch mixture, whisking to combine. Bring to a simmer, keeping heat at medium-high. Cook, stirring constantly, until mixture has thickened, about 2 minutes. Remove from heat, and set aside until ready to assemble the enchiladas.