Cut the Scallion (1 bunch) to separate the dark greens and whites. Thinly slice the whites and light greens. Set aside.
Add the scallion greens, Mirin (1/2 cup), Soy Sauce (1/2 cup), Sake (1/4 cup), Vegetable Bouillon Cube (1), and Brown Sugar (1 teaspoon) to a saucepan. Bring to boil. Lower to simmer. Simmer until reduced by half.
Remove from heat, discard the scallion greens, and set aside.
Heat the Sunflower Oil (2 tablespoon) in a large pan or wok over medium-high heat.
Add the white parts of the scallions, Garlic (3 clove), Fresh Ginger (2 tablespoon), and Crushed Red Pepper Flakes (1 teaspoon). Cook 1-2 minutes until aromatic.
Add the Orange Bell Pepper (1), Red Bell Pepper (1), Broccoli Rabe (1 bunch), and Snow Peas (1 cup). Cook 2-3 minutes until tender.
Turn up the heat to high. Add the contents of the saucepan. Let it come to a simmer. Add the Zucchini (4). Mix well. Cook 2-3 minutes. Enjoy!