Sweet roots turned into a wonderfully crunchy snack

Serves 6
3 large parsnips
3 large beetroots
3 large sweet potatoes
Vegetable oil
Sea salt
1 tbsp fennel seeds

1 Preheat oven to 150C/Fan 130C/ 300F. Line 4 baking sheets with baking parchment (or if short of space or trays, cook crisps in batches).
2 In a small bowl, mix 3–4 tbsp of vegetable oil, the fennel seeds and a good grind of salt. Lightly brush the baking parchment with the oil mixture. Set aside.
3 Use a mandolin or vegetable slicer attachment on a food processor or, failing that, slice all the vegetables as thinly as possible. Use kitchen towel to pat slices dry.
4 Place the vegetable slices on your baking sheets, making sure they don’t overlap. Then lightly brush the crisps with the oil mixture.
5 Bake for 1 hour; after an hour, remove the parsnips, returning the beetroot and potatoes to the oven for another 30 mins. Cool on a rack, and store in an airtight container.

Turn to page 24 of August's The Simple Things for more of our picnic in the park menu, including: