Toss the coriander seeds and cloves in a 6-quart pressure cooker. Press the sauté button on your Instant Pot (or place a stovetop pressure cooker over medium heat) and toast the spices for several minutes, shaking or stirring, until fragrant. Throw in the ginger and onion and stir everything until aromatic, 45 to 60 seconds.
Pour in 4 cups (1 l) of the water to stop the cooking process. Carefully place the chicken in the cooker, breast side up.
Add the apple, cilantro, salt, and remaining 3 cups (0.71 l) water.
Press the Cancel/Keep Warm button, lock the lid in place, and make sure the valve on top is in the sealed position. Press the Manual button and set the Instant Pot to cook under high pressure (~12 psi) for 14 minutes.
If you’re using a stovetop pressure cooker, bring to low pressure, 8 psi, over high heat on a gas or induction stove, or medium heat on an electric stove. Lower the heat to maintain pressure, signaled by a gentle, steady flow of steam coming out of the cooker’s valve. Cook for 15 minutes, or a few minutes longer if your cooker’s low setting is less than 8 psi. If your cooker only has a high-pressure,15 psi, setting, cook for 12 minutes. Your aim to gently poach the chicken and not overcook it!
When done, turn off the Instant Pot and let the pressure decrease naturally for 20 minutes. Set a timer and if the pressure hasn’t completely released when it dings, turn the valve at the top to quickly vent the remaining pressure. (If you’re using a stovetop pressure cooker, slide it to a cool burner and let the pressure decrease naturally, about 20 minutes.) Remove the lid, tilting it away from you to avoid the hot steam.
Wait another 5 minutes before using tongs to transfer the chicken to a large bowl; if parts fall off in transit, don’t stress. Add cold water to cover the chicken and soak for 10 minutes to cool and prevent drying. Pour off the water, partially cover, and set the chicken aside to cool.
Skim some fat from the broth, before straining it through a Chinois or muslin-lined mesh strainer positioned over a large pot. Discard the solids. You should end up with about 7 cups broth.
If using right away, season the broth with the fish sauce, extra salt, and maybe a smidge of the maple syrup. Or, partially cover the unseasoned broth and let cool, then refrigerate for up to 3 days or freeze for up to 3 months; reheat and season before using.
Use a knife or your hands to separate the breast meat and legs from the chicken. Set aside half of the chicken for another use. Reserve the remaining chicken for pho bowl assembly. The chicken can be refrigerated for up to 3 days or frozen for up to 3 months; bring to room temperature to use.
Prep and assemble the bowls. Cut or shred the chicken into bite-size pieces. Discard the skin or save it for cracklings. Bring the broth to a simmer over medium heat as you are assembling the bowls.
Divide the zucchini noodles among four soup bowls. (If you like softer zoodles, use a mesh strainer to dunk them in boiling water until the desired softness before placing the drained zoodles into the soup bowls.) Top the zoodles with shredded chicken.
Check the broth flavor once more, raise the heat, and bring it to a boil. Ladle about 2 cups (480 ml) broth into each bowl.
Then garnish with onion, green onion, cilantro, basil, pepper, and sriracha if desired. You can squeeze on fresh lime juice, too. Serve immediately!