I only boil mine until I can just poke a fork in them, still a little tough but not hard.  I use a generous amount of oil so that all sides of the potatoes are coated.  Mine seem to be just fine.

Welcome to the forum zacg777

A lot also depends on the type of potato that you are using, waxy potatoes dont roast well floury potatoes roast well. I mostly buy Maris Piper for roasting.

Like the others have said, boil them ( and yes I do sometimes overboil them a bit    .. just as well my family really love all those little crispy bits that then happen from the broken potato pieces !!!)

Like Olivia, I also let the potatoes steam off a little before I put them into the hot fat.

I mostly use Trex for roasting the potatoes, Trex is a solid vegetable fat and makes very good roast potatoes. ( I don't use oil )

Once I put the potatoes into the hot fat , I turn them so that they are all coated with the molten fat and then scatter them with salt .
I dont use too much fat , just enugh so that the potatoes get a light coating of fat over them but are not sitting in puddles of fat , if yu know what I mean.
I cook them in a reasonably hot oven in a roasting tray with sides . those roasting  trays wih slightly slopeing sides are best as they don'tt trap the stam that comes from the potatoes as they roast.

They can cook for quite a long time before they start to spoil .

What potatoes do you use zacg777 ?

Some good advice here - agree that it's important to let the moisture steam off after boiling. If they're still giving off steam when they hit the fat, they won't get crispy.

The other important factor is screaming hot fat. I like to get it nice and hot in the oven, then put the roasting tray on the stove while I'm adding the spuds. Obviously you need a sturdy metal roasting tray to do this - but by heating on the stove, you make sure that the oil is sizzling when you add the spuds.

But to answer your questions (drawing heavily on Delia Smith) -

- Don't boil your potatoes for too long - they tend to fall apart. Test them by running a knife point along the surface - if you get a fluffy line, they're done. Then, as you say, rough them up before roasting.

- It's less about the quantity of fat and more about the temperature. Hot fat will form the nice, crispy coating you're after. If the fat's not hot enough, the spuds will absorb it and get greasy and soggy. Make sure the oven is nice and hot, and remove your potatoes from the oil as soon as they're done (once out of the fat, you can keep them warm until ready to serve). Drain on kitchen paper.

- Best oven temp is 220C, or 200C for fan ovens.

Something else to consider is the type of potato - for example, Maris Pipers are a good, reliable roasting spud. And try flavouring your oil - I like to chuck in some fresh rosemary and a couple of cloves of garlic.

Well, I know people are fond of parboiling but I never do this.  I have done it and I am not happy with the results.  I've experimented with roasting potatoes for years because roasted potatoes are by far my favorite food on earth.  I've tried all kinds of potatoes and all kinds of methods and have found the method I love best.

Waxy potatoes are good for roasting, they hold their shape but stay rather firm which can be nice sometimes.  My favorite is yukon gold potatoes, they are not as starchy as the all-purpose but they do fall apart easily.  Their flavor is unbeatable.

I NEVER parboil.  I toss into a pan, raw with olive oil and butter and herbs and seasonings.  Cover with foil and put into a 400F convection oven for about 45-60min.  Then uncover and let them get golden.

You see, the potatoes have lots of moisture inside them, they do not need to be boiled imo.  They steam in their own juices and really taste like a potato.  Not a fan of parboiling, they end up tasting boiled to me.  That's just my opinion though.

The good thing about potatoes is that they are relatively inexpensive so you can really experiment endlessly.

Just to add I rather like waxy roasties as well, a different experience from fluffy ones but very good in their own way. I get charlottes or the ones labelled as "salad potatoes" or "new potatoes", cut them in half, toss in oil and salt and roast at about 220C for 20-30 min. I don't parboil them, or peel them as I like the skin. Give it a try.