Cook the rigatoni according to packaging instructions. When it is ready, drain it and retain ¼ cup of the cooking water. 

Heat the olive oil in a pan and cook the garlic for 1-2 minutes, until fragrant. Now, add the carrot and bell pepper, cooking for 3-4 minutes more, until they start to soften. 

Next, add the coconut milk, nutritional yeast, and salt. Stir for a minute, then add the cooked pasta, pasta water, lemon juice, dry basil, and cornstarch. Stir for 2 minutes more, until the sauce thickens.