Preheat oven to 400 degrees Fahrenheit and line a baking sheet with parchment paper or a non-stick baking mat.
Cut the cauliflower into medium sized florets. Try to remove as much of the stalk as possible. Put the cauliflower florets in a bowl and toss with a 1/2 tablespoon of peanut oil and 1/4 teaspoon salt until they are evenly coated.
Spread the cauliflower florets onto the lined baking sheet and place in the oven. Roast for 20 minutes or until the florets begin to get brown along the edges.
Let the cauliflower cool for ten minutes. Take a small handful and place in a blender or food processor. I use a blender and you should be able to see the tips of the blades. Pulse for a few seconds on low speed (a 3 if you have a Vitamix). The cauliflower should have the texture of rice. Pour into a bowl. Repeat until you have "riced" all the cauliflower.
Heat a 1/2 tablespoon of peanut oil in a skillet on medium heat. Add the onions and sauté them until they are soft. Add the frozen peas. cook until the peas aren't frozen anymore.
Add the sautéed onions and peas to the bowl of cauliflower rice. Mix well. Add lime zest and salt and pepper until you get the taste you want.