Remove the vein from the shrimp, rinse, and pat dry. Marinate with sake, salt, and pepper.

Cut broccoli into bite-sized florets. Thinly slice the onion and mince the garlic.

Boil water in a pot and cook spaghetti 1 minute less than package instructions. Add broccoli 2 minutes before the spaghetti finishes cooking. Drain well.

Heat olive oil and garlic in a pan over low heat until fragrant. Add shrimp and cook over medium heat until white, then remove.

Add onion to the pan and sauté over medium heat until softened. Add soy sauce, anchovy paste, and salt and pepper, mixing well.