Cut the cauliflower into small pieces, and add it to a big mixing bowl.
Add the oil and the seasonings to the bowl and mix well.
Transfer the cauliflower bits into a cookie sheet and bake for 25-30 minutes until the cauliflower is golden brown.
Prepare the dressing by whisking together the mayonnaise and mustard until creamy.
Once done, remove the cauliflower and let it cool for 10 minutes. Then, transfer it into a mixing bowl, add the dressing and toss everything together until combined.
Optional: garnish with diced onions, and additional seasonings of choice.