Place sea bass fillets and shrimp onto a plate. Mix Japanese sake, soy sauce, and potato starch (or cornstarch) in a bowl until fully incorporated. Pour over the seafood and gently mix by hand. Let marinate for 10 to 15 minutes.
Heat olive oil in a dutch oven (or a skillet large enough for stew) over medium heat until warm. Add garlic and onion. Cook and stir until tender.
Add green beans. Cook for 4 to 5 minutes.
Add mushrooms and artichokes. Cook and stir until the beans turn soft, 4 to 5 minutes.
Add broth, dried marjoram, tarragon, thyme, and garam masala. Cook until boiling.
Add seafood, along with all the liquid, into the pot. Let simmer until the seafood is just cooked through, 2 to 3 minutes.
Adjust seasoning with salt. Gently mix the broth with a spatula. Be careful not to overcook the fish, or it will fall apart.