Preheat broiler to high.
Stud onion with cloves and place on baking sheet with chicken and garlic. Broil for 10 minutes or until charred, turning chicken and vegetables over halfway.
Meanwhile, place cardamom, cinnamon stick, and star anise in a small pan and heat over low heat. Toast spices until aromatic, about 4-5 minutes. Remove from heat and place spices in cheesecloth, binding the cloth with string.
Place spices, charred chicken and vegetables in large pot. Fill with 12 cups water, cover and bring to a boil over high heat. Reduce heat to low and continue to simmer for 1 hour.
Make coconut crisp. Heat 2 tablespoons oil in small saute pan over low heat. Add sliced garlic and cook until lightly golden, about 3 minutes. Add coconut and cook until golden brown. Remove from heat and place on paper towels to drain excess oil. Let cool.
Strain chicken stock, reserving chicken and discarding aromatics. You should have about 10 cups stock. Bring stock back to a simmer and add chopped Thai chilies, rock sugar, soy sauce, fish sauce, and lime juice. Season with salt and pepper. Shred chicken into bite-size pieces.
Cook vermicelli noodles according to directions on package. Drain and portion noodles into bowls. Ladle soup into bowls and top with chicken, bean sprouts, Thai basil, cilantro, mint, and sliced jalapeno. Serve with lime wedges on the side.