Heat oil in a soup pot and sauté onions over medium heat for about 5 minutes, stirring occasionally. Using your hands, roughly crumble fideo nests into the hot oil, and fry the dry pasta, stirring frequently, until it is golden brown. This will take about 10 minutes. Do not scorch noodles.
Add tomatoes with juice, and crushed garlic; stir over heat to coat noodles, then add chicken broth and stir. Add half the bag of chard without stirring (save rest for another use), cover pot and bring to a boil. After a minute or two, open pot and press chard down into the noodle mixture with a big spoon. Cover pot and boil gently over low heat for 10 minutes.
Remove from heat, taste and add salt and freshly ground pepper if needed. (Be careful about adding salt because chicken broth and tomatoes will be salty.)
Note: If you cant find the canned tomatoes with jalapeno, substitute a can of plain diced tomatoes in juice or Italian-style diced tomatoes, and add a finely minced jalapeno (seeds removed) during the stage where you are sautéing the onion. Or instead of the fresh jalapeno, substitute a 4-ounce can of mild green chiles if you want a milder chile flavor.