In a large skillet over medium-high heat, cook the chorizo, breaking up as it cooks. Once cooked through and broken apart, transfer the chorizo to a bowl, leaving the rendered fat in the skillet. 
Add half of the onion, half of the jalapenos, all of the poblano, and all of the garlic to the skillet over medium heat. Cook, stirring occasionally until very soft, about 10 minutes. Stir in half of the tomatoes. Season with salt. Cook, stirring occasionally, until the tomato juices evaporate, about 6-8 more minutes. 
Meanwhile, combine the remaining tomatoes, onions, and jalapenos in a small bowl. Add in the chopped cilantro and lime juice. Season with salt, to taste. Mix well and set aside until ready to serve.
Pour the evaporated milk into the skillet. Let warm.
Toss the grated cheese in a large bowl with the cornstarch. Add the cheese, one handful at a time, to the skillet, stirring to melt as you go. Continue to stir until fully melted and thickened to coat the back of a spoon. Remove from heat. 
Top with the crumbled chorizo, pico de gallo, additional cilantro, and sour cream, if desired, to serve. Serve warm.