In this tasty dish, ancho chile peppers, rehydrated in tangy-sweet piloncillo-sherry vinegar water, are filled with creamy corn and baked.
In a medium-sized saucepan, heat the chicken stock, 1 pound of the corn kernels, and 1⁄3 cup of the cream over medium-high heat for 1 minute. Scrape the mixture into the container of a food processor, add the remaining cream, and purée until smooth.
Melt the butter in a large saucepan over medium heat. Stir in the onions and sauté until soft. Add the garlic and cook for 1 more minute. Add the remaining corn and poblano chiles and heat gently.
Stir the puréed mixture into the corn-poblano mixture, lower the heat, and simmer for about 10 minutes, stirring occasionally to avoid sticking and burning. Season with salt and pepper, to taste. Add the cilantro and keep warm.
Preheat the oven to 350 degrees.
Line a baking sheet with parchment paper, and lightly oil a baking dish. Combine the water, vinegar, piloncillo, and salt in a medium-sized saucepan and bring to a boil over high heat. Reduce heat to a simmer and cook until the sugar is melted, about 2 minutes.
Toast the chiles and put them in a nonreactive bowl. Pour on the piloncillo-sherry mixture and soak until rehydrated, 20-30 minutes. Remove from the liquid, make a slit from stem to tip in each chile, and remove the seeds and veins. Any discards from the chiles should be chopped and folded in with the filling. Lay the chiles on the baking sheet and cover with a damp towel. Reduce the soaking liquid over medium-low heat into a syrup, 15-20 minutes; strain and reserve.
Fill the chiles with the creamed corn mixture, lay them in the baking dish, transfer to the oven, and heat until warmed through, about 15 minutes. Toss the spinach and charred onions with a little of the reserved sherry-piloncillo syrup mixed with the lime juice; serve on individual plates.
Place the hot chiles on top of the salad, pushed open slightly like a baked potato, and garnish with cilantro. Drizzle the sherry-piloncillo reduction over the plate and serve.