Heat oil in a large frying pan over medium-high heat. Add onion, poblano, and garlic and cook, stirring often, until softened, about 10 minutes. Add chuck, ground chiles, cumin, and salt and cook, stirring to break beef apart, until no longer pink, about 5 minutes. Add crushed tomatoes, vinegar, raisins, and olives and cook until most of the liquid has evaporated, about 3 minutes.
Preheat oven to 400°. On a lightly floured surface, roll puff pastry to 1/8 in. thick. With a 3 1/2-in. cutter, cut as many rounds as possible, rerolling and cutting remaining dough. Spoon a scant tbsp. filling onto each round, fold dough over filling to make a half-moon, then seal and mark edges with the tines of a fork. Beat egg with 1 tbsp. water and brush over pastry tops.
Set empanadas on oiled baking sheets and bake until golden brown, about 20 minutes. Serve warm with Chimichurri.
Chimichurri In a food processor, combine 1 cup each packed parsley sprigs and cilantro sprigs, 2/3 cup extra-virgin olive oil, 6 tbsp. white wine vinegar, 2 tbsp. fresh oregano leaves, 4 garlic cloves, 1 tsp. kosher salt, and 1/4 tsp. red chile flakes. Pulse until herbs and garlic are finely chopped. Let sit at least 1 hour.
Note: Nutritional analysis is per empanada without chimichurri.