I can say that when I lived in Britain that I had the best roasted potatoes of my life. As part of a Sunday dinner or is the Brits call it a “roast dinner”. The potatoes were always a highlight, and I could never figure it out until a friend told me what I was doing wrong.
When you want potatoes that are super crispy on the outside and very tender and creamy on the inside then you need to follow a two-step process.
Here’s the secret to the crunchy outsides and creamy insides:
It’s very simple, the key is to add a little bit of baking soda into the water when you par boil the potatoes. Normally 1/2 a teaspoon is plenty. More than that and you can get a flavor from the baking soda. That’s not pleasant. 
First you’re going to parboil the potatoes, then you’re going to drain them, rough them up in the pan and then turn them out onto a baking sheet and add the other ingredients. The results are spectacular.
Ingredients:
1-2 lbs of Yukon Gold potatoes, cut into quarters.
1/2 tsp Baking Soda
2 Tbsp Salt
3 Tbsp of Goose or Duck fat. If you don’t have that, you can also use a vegetable oil, but the taste really isn’t the same.
Fresh Thyme and Rosemary are perfect.
Salt and Black Pepper
Preparation:
Preheat your oven to 400F.
Par boil the potatoes with salt and baking soda for 6-8 minutes depending on the size. Don’t cook completely. Drain and allow to rest for a minute.
Then pour back into the pan and stir them to rough them up. You want those little bits of potato to adhere to the bigger pieces. That is what’s going to create the amazing crunch.
Add your herbs, the fat and into the roasting pan for 40-60 until crispy and golden brown.
Note: It might be tempting to use butter, but it will burn. If you’re really wanting to use butter, then you need to use clarified butter, because it has a much higher smoke point. Ghee, which is available a lot of places now, is effectively clarified butter, and regularly used in Indian cooking. 
British Style Oven Roasted Potatoes
Ingredients
Equipment
Method
- Preheat your oven to 400F.
- Par boil the potatoes with salt and baking soda for 6-8 minutes depending on the size. Don’t cook completely. Drain and allow to rest for a minute.
- Then pour back into the pan and stir them to rough them up. You want those little bits of potato to adhere to the bigger pieces. That is what’s going to create the amazing crunch.
- Add your herbs, the fat and into the roasting pan for 40-60 until crispy and golden brown.