Place a large stock pot over medium heat. Add the onion wedges, ginger, garlic, cinnamon, star anise, cloves, cardamom, and coconut oil. Sauté the onions and spices for about 10 minutes, stirring to brown the onions on all sides.
Pour in the water, beef broth, fish sauce, and sugar. Bring to a simmer. Then lower the heat if needed, and simmer for at least 60 minutes. (P.S. Fish sauce has a funky aroma, but tastes amazing! Don't skip it.)
Meanwhile, flash-freeze the flank steak for 30 minutes. It should be frozen on the outside, yet still mostly thawed on the inside. Then slice the steak against the grain into paper-thin pieces.
Use a skimmer to pull all the onions, and spices out of the broth. Then arrange the mung bean sprouts, sliced jalapeno, lime wedges and basil on a serving plate.
Add in the noodles to the broth and cook for 2-3 minutes, or according the the package instructions.
Turn off the heat and stir in the thin pieces of beef. They should be thin enough to cook in the hot broth without additional heat.
Scoop the pho into bowls and allow guests to add their own veggie garnishes.
A. If you can't find shirataki noodles, you can add raw zucchini noodles instead. B. If "low carb" is not necessary for your diet, rice noodles are traditional. C. The longer the broth cooks the better. You can turn the heat down to low and allow it to simmer for 2 hours. Or make it a day ahead for intensified flavor, before adding the noodles and beef.D. Slow Cooker Pho Soup:Yes, you can make this recipe in a crockpot. Make sure to sauté the vegetables and spices on the stove top first. Then slow cook the broth up to 12 hours on low, before moving onto to step 4.