Preheat the oven to 425°F (220°C). Place the onion, tomatoes, garlic, ancho chile and olive oil in a medium bowl and toss until all veggies are coated in oil.

Spread into a single layer on a parchment-lined baking pan and roast for 25-28 minutes, turning the vegetables once at the 15-minute mark, until softened and lightly charred in spots. Remove from the oven and let cool for 5 minutes.

Transfer the roasted vegetables and chile to a blender and blend until completely smooth. Set aside.

Heat olive oil in a large pot over medium heat. After 90 seconds, when the oil is hot, add the cumin, coriander, oregano, and black pepper. Stir constantly for 30 seconds until fragrant.

Add the fideo noodles and stir to coat evenly in the oil and spices. Cook for 3 minutes, stirring every 30 seconds, until the noodles are lightly toasted.

Add the vegetable broth, pureed roasted vegetables and salt. Stir thoroughly, bring to a steady simmer over medium heat, then reduce to medium-low heat and cook for 8-10 minutes, stirring occasionally, just until the noodles are tender.

Serve hot on its own or garnished with white onion, cilantro, vegan sour cream, and lime wedges.