Make the curry sauce: In a large sauté pan, whisk together the curry paste, coconut milk, lime zest, lime juice, fish sauce, and desired amount of red pepper flakes (use ½ teaspoon for mild heat, 1 teaspoon for medium, or 2 teaspoons for hot). Let simmer over medium-low heat, stirring often, until it is thick enough to coat the back of a spoon. This will take about 20 minutes.
Make the rice: If using white rice, prepare according to package. To make cauliflower rice, remove florets from the stem. Affix the grating attachment to your food processor and run the florets through. It will result in "ricing" the cauliflower. If you don't have a food processor, you can grate the cauliflower by hand using a box grater. Set aside.
While the sauce is simmering, prepare the rest of the ingredients: In a frying pan, cook the onion in the coconut oil over medium heat until translucent and slightly brown. Add the chicken and cook on medium-high for about 5 minutes each side, or until each piece is completely white and cooked-through. Transfer the chicken and most of the onions to a bowl. Add the bell peppers to the frying pan. Cook the peppers over high heat for about 10 minutes, or until they’re wilted and slightly browned on a couple sides.
When the curry sauce has thickened, add the chicken, bell pepper, and onion mixture to it. Stir to incorporate and let simmer for 5 minutes. Add the basil and let simmer for 2 to 3 more minutes.
While the chicken and veggies are simmering in the sauce, heat up the cauliflower rice. Place the riced cauliflower in the same frying pan used to make the chicken and veggies over medium heat. Let cook for 5-10 minutes until cauliflower is cooked through.
Serve curry warm over cauliflower rice. Garnish with fresh basil leaves and a lime wedge.