Scrub mussels and remove their beards.

Heat peanut oil in a wok or large frying pan over medium-high heat.

Add crushed garlic and ginger to the hot oil and stir-fry until fragrant (about 1 minute).

Pour in maple syrup, soy sauce, oyster sauce, fish stock, and lemon juice.

Bring the sauce mixture to a boil.

Add the scrubbed mussels to the boiling sauce.

Reduce heat to medium and cover the wok or pan.

Simmer the mussels for approximately 5 minutes, or until they have opened up. Discard any mussels that remain closed.

Remove the cooked mussels from the pan and cover them to keep them warm.

Return the remaining stock mixture in the wok to a boil.

Add chopped bok choy, gai lan, and bean sprouts to the boiling sauce.

Stir-fry the greens until they are just wilted (about 2-3 minutes).

Return the cooked mussels to the wok with the stir-fried greens.

Stir-fry until the mussels are heated through.

Serve immediately with steamed Jasmine rice if desired.