Toast 8 ounces fideo or broken spaghetti in a skillet with olive oil over low heat, 4 minutes. Stir in 1 cup chopped scallions and 2 teaspoons ground cumin. Add 1 1/2 cups chicken broth and one 14-ounce can diced tomatoes with chiles. Simmer, stirring, until the noodles are tender, 12 minutes. Season with salt. Top with chopped cilantro and crumbled Cotija cheese.