Slow-Cooker Pho - cooking recipe

Ingredients

2 medium onions, peeled and quartered
1 head garlic, split horizontally
one 4-inch piece ginger, split in half horizontally
2 serrano chilies, split in half horizontally, plus 2-3 additional, thinly sliced, for serving
2 cinnamon sticks
4 star anise
2 1/2 teaspoons coriander seeds
7 cloves
1 tablespoon black peppercorns
2 teaspoons fennel seeds
5 cardamom pods
three pieces bone-in beef shank, cut into 2-inch rounds, about 5-6 pounds total
8 cups low sodium chicken broth
2 teaspoons salt or 2 teaspoons fish sauce, plus additional for serving
1 lb thin rice noodles, soaked in hot water until tender for 30 minutes
1 cup bean sprouts, for serving
lime wedge, for serving
mixed herbs, such as cilantro, Thai or italian basil, and mint, for serving
thinly sliced scallion, for serving

Preparation

Preheat broiler.
Place onion, garlic, ginger, and serrano chiles on a small baking sheet and broil, rotating until charred, about 8 minutes. Remove from broiler and add cinnamon, star anise, coriander, cloves, peppercorns, fennel, and cardamom. Return to broiler until spices are toasted and aromatic, about 30 seconds to a minute more. Transfer to crock pot, along with beef shanks and chicken stock. Add salt or fish sauce, and enough water to cover shanks by 1/2-inch, about 8 cups.
Place lid on crock pot and let cook, at least 8 hours and up to 12 for an even fuller flavor, until meat is falling off the bone.
Remove beef from crockpot. With a spider or mesh strainer, remove all aromatics from the pot. With a large spoon, skim fat. When beef is cool enough to handle, shred into bite-sized pieces and return to broth. For best results, chill broth and skim fat; reheat before serving. Alternatively, skim fat while soup is warm with a large spoon. Season to taste with salt or fish sauce.
Divide broth and meat among serving bowls and top with noodles, bean sprouts, lime wedges, herbs, scallions, and chiles. Serve.