Cut bell pepper into short strips. Cut carrot und zucchini into slices. In a bowl, stir coconut milk until you have a smooth consistency. Heat up vegetable stock and keep warm.
In a small pot, warm olive oil over medium heat. Saute curry paste for 1 minute while stirring. Whisk in half of the coconut milk until combined and cook for 5 minutes. Stir occasionally.
Add vegetable stock, salt, soy sauce and sugar and bring to a boil. After that, add the rest of the coconut milk, bell pepper, carrot and zucchini and mix together. Let cook for 5 minutes.
Remove the pot from the heat and add basil.