Bring a large pot of water to a boil and cook the udon noodles according to the package instructions until al dente. Once cooked, drain them in a colander and set aside.
In a large frying pan or wok, heat the olive oil over medium heat. Add the sliced onion and sauté for about 3-4 minutes until it becomes translucent and soft.
Stir in the minced garlic and continue cooking for an additional minute, letting the garlic become fragrant.
Increase the heat slightly and add the julienned carrot and sliced bell pepper. Stir-fry the vegetables for approximately 5 minutes, allowing them to become slightly softened but still crisp.
Add the fresh spinach to the pan, cooking it for about 2 minutes or until it wilts down, incorporating it with the other vegetables.
While the vegetables are cooking, prepare the creamy sauce. In a small bowl, whisk together the gochujang, coconut milk, soy sauce, sesame oil, and honey (or maple syrup) until you achieve a smooth consistency.
Pour the prepared creamy sauce over the sautéed vegetables in the pan. Mix well and let it heat for about 2 minutes, allowing the flavors to meld together.
Gently add the cooked udon noodles into the pan, carefully tossing everything together until the noodles are fully coated in the rich sauce. Heat the combined mixture for another 2-3 minutes, adjusting the seasoning with salt and freshly ground black pepper to your taste.
Once everything is heated through and well combined, remove the pan from the heat and prepare to plate the dish.
Serve the creamy gochujang udon in bowls, generously garnishing with sesame seeds and chopped green onions for an appealing finish.
Notes
Adjust the spice level by varying the amount of gochujang used.