No, that is not the prep step. The prep step starts with all of these done and is mixing all of these together in a zip lock bag and putting it in the fridge. So 5 minutes seems even a bit high.

The time for recipes is always "with all ingredients washed, peeled, chopped and set ready to go in a bowl. Start!". Also note that step 2 is to put the onions into the pan (but no step says to cut onions) and that the ingredient list says "garlic, peeled, finely grated" and not "garlic" and "onions, sliced thinly".

You might not like that convention of "time" or would like "actual time" in addition, but it is a pretty universal convention. And it makes sense: the prep time can vary wildly (e.g. peeling and chopping veggies) making the "actual time" quite useless and in professional kitchens other people do this prep work.

So hard disagree from me. The time seems pretty spot on.