Heat the vegan butter in a large skillet over medium heat. Add the onion and cook for about 5 minutes until softened.
Stir in the rice, carrot, bell pepper, garlic, thyme, rosemary, and basil. Cook for 2 to 3 minutes until the rice is lightly toasted.
Add the vegetable broth, diced tomatoes, salt, and black pepper. Bring to a gentle boil.
Reduce the heat to low, cover, and simmer for 10 minutes.
Stir in the zucchini, cover again, and cook for another 5 minutes.
Remove from the heat and let the pilaf rest, covered, for 10 minutes.
Fluff the rice with a fork, then stir in the lemon juice and fresh parsley. Taste and adjust the seasoning before serving.