Heat 1 tablespoon of oil in a large skillet over medium-high heat. Add 1/2 cup of diced onion and 1/2 cup of diced bell pepper and cook for about 5 minutes until softened. Add 1 cup of diced mushrooms, 1/4 cup of diced carrot, and 1/4 cup of diced zucchini to the pan and cook for an additional 5 minutes. Add 1 tablespoon of grated fresh ginger, 2 cloves of minced garlic, 1 teaspoon of sesame oil, 1 teaspoon of soy sauce, and 1/4 teaspoon of crushed red pepper flakes to the pan and cook for 1 minute until fragrant.