Set a large pot or Dutch oven on the stove top over medium-high heat and add the butter. When the butter is melted, add the onion, celery, and carrots. Cook for 3 minutes, stirring frequently, until softened slightly.
Sprinkle the flour and curry powder over the vegetables and stir to coat. Cook for 1 minute.
Add the vegan chicken broth, cauliflower, rice, apple, black pepper, and thyme. Bring to a boil, then reduce to low heat.
Cover and simmer for 15 minutes, until the rice is cooked.
Remove from heat and stir in the half-and-half.
Adjust seasoning to taste, sprinkle with cilantro, and serve hot.