Wash the spinach.
Pour a small amount of oil into a frying pan and add the pine nuts. Stir them constantly until they have browned then set them aside.
For the sweet potato chips:
Peel the sweet potato then slice it very finely using a mandolin.
Heat plenty of oil in a pan over a medium heat.
After 10 minutes, add the sweet potato slices to the oil. Once they have browned, remove and set them aside to cool.
Make a vinaigrette with two parts oil to one part vinegar.
Clean and halve the tomatoes.
Put the salad leaves together and dress with the vinaigrette.
Add the salt, pine nuts and top with 3 sweet potato crisps per person.