It sounds to me like the issue may be that you're crowding the pan.
Basically, to get everything nice and brown and crispy, you need enough space for all of the steam to escape. That picture you showed has potatoes stacked on top of each other -- that means as the bottom items cook, they're going to end up steaming the items above them.
At a diner, they have a large griddle to work with -- they can really spread things out. You're not typically that lucky in a regular kitchen, as you don't have as much space, and you have a lip on the pans that'll hold the steam in.
So, either work in smaller batches, or consider recipes that use an oven -- using sheet pans instead of a pan on the stove solves much of the problem.
One other trick is that most diners don't start from raw potatoes -- maybe with hash browns, but not for home fries, you're not going to get the nice soft interior in a reasonable amount of time unless you start with a potato that's already been baked or boiled. (If you're doing things in the oven, you might be able to, but not in a pan)
Just for reference ... I have a 14" cast iron skillet that I use for home fries ... and it's about the right size for cooking a single large potato, which might be two servings, maybe three for kids. (I tend to cook carb-heavy meals).
update : I probably should've stated this directly -- you want the chunks of potato to form a single layer in the pan, with space in between them.
In the general case, it is not possible.
As you cook meat past about 165 F, all of the proteins will have denatured and contracted, squeezing out moisture. This is what makes well done meat tough and stringy or rubbery. This process cannot really be reversed, although you can try to mask it with a sauce.
In the specific case of certain cuts--the ones famous for braises or barbecue, the "low and slow" cooking techniques--there is some hope, but it is a thin one depending on what you have been doing.
These cuts, the most active working parts of the animal such as the shoulders (chuck for beef or butt for pork) have a great deal of intramuscular fat, as well as connective tissue made of a protein called collagen.
Over time, when cooked slowly at temperatures of about 180 F, the collagen in the meat will turn into gelatin, which has a silky, smooth mouth feel, and the fat will lubricate the meat. They still have their proteins irreversibly dentures and tightened, but the gelatin and fat provide a new kind of moisture and unctuousness that is highly prized.
The cooking techniques for this (braising, barbecuing, slow roasting) are rarely employed for chops or steaks that you would do in the frying pan. They also simply don't have the collagen or the fat to make it possible. That is why they are better off with the higher temperature, faster cooking methods, but should not be overcooked, as you have discovered to your dismay.
Your best option is not to try to recover from this situation, which is very difficult to do, but rather to learn to prevent it:
- Get a good instant read thermometer to check the internal temperature of your steaks or chops
- Learn what the safe temperature is for that type of meat. For example, poultry and pork should both be cooked to at least 155 F (and for poultry, many people have learned to like even more done meat)
- The FDA recommends 165 F for ground meat (which is quite well done)
- Measure the temperature of your meat and learn to recognize when it is done
- Assess what level of risk you are willing to accept
Over time, you will learn to recognize when cuts are done to your liking by how they feel when you poke them with your finger (which is a pretty good indication of how done they are, based on how resilient they are), but the thermometer will be your guide until you build that experience.
Still, this will require that you adjust your expectations of what completely cooked meat looks like. Pork may still be a touch rosy, for example.
Best Answer
When meat and poultry are tough it is because because of connective tissue which transfers the muscle's work to bone. The harder a muscle in an animal works the more connective tissue it will have and the tougher (but generally more flavorful) the result will be. Connective tissue (collagen mostly in muscles) breaks down slowly in the presence of moisture and heat.
Frying is too short a cooking process to break down collagens, you need a low and slow method. If it were me I'd braise it instead of roasting it, so I'd coat it in flour and fry it off in a pan, then bake low (maybe 225f or 100c) it in a covered pan with a 500ml (about a pint) of chicken stock and a bit of rubbed sage for about 3 hours. If that doesn't make a tender rooster nothing on earth will.