To make the Mexican noodle soup, first blend the onions, garlic, tomatoes and chipotle until smooth.
Heat oil in a large, heavy saucepan. Sauté noodles and pork, cut into about 1-inch cubes, until noodles are golden (5 to 7 minutes). Pour in tomato puree and chicken soup and bring to a boil. Simmer without the lid for about 5 minutes, until the noodles are al dente. Season with salt.
Arrange the Mexican noodle soup in plates and bring to the table immediately.