Leek, potato and kale soup

SOURCE This recipe comes from Beach House Kitchen. We have tweaked the recipe very slightly and made some of the steps more explicit for the novice cook.
Serves 4 as main course, 8 as starter
Time (approx): preparation 20m cooking 30m

1 tbsp vegetable oil
750g leeks
1.25kg potatoes
1.5 litres vegetable stock*
1 tbsp fresh / 1 tsp dried sage**
1 tbsp fresh / 1 tsp dried rosemary**
1 tbsp fresh / 1 tsp dried thyme**
2 bay leaves
200g kale leaves
250ml single cream or milk
Salt and black pepper (optional: to taste)
* Mix 2–3 tbsp Seven Acres vegetable stock concentrate with 1.5L water.
** If these herbs are not to hand, use others that would blend in well, e.g. parsley, coriander, tarragon.
Knife with a sharp blade
Plastic or wooden spoon or spatula for stirring
Large saucepan.
Blender or food processor.
A hob or other direct heat source; space to chop.
Advance preparation
None required.
Preparing the Vegetables
Top, tail and wash the leeks, then slice them.
Peel the potatoes, then chop into pieces roughly 1" each side.
Wash and drain the kale, then slice.
Cooking the meal
Add the cooking oil to a large saucepan and warm on a medium high heat. Add the leeks, cover and cook for 5 minutes.
Add the potatoes, stock, bay leaves and other herbs to the saucepan; cook for 10–15 minutes, until potatoes are tender.
Add the kale and simmer for a couple of minutes. Pick out the bay leaves and blend until smooth.
Stir in the cream or milk. Serve, then season to taste with salt and pepper if required.