Cut off the tops of the fennel bulbs and slice thinly into rings. Place into a large bowl.
Cut away the skin and pith from one orange and slice into circles 1cm/½in thick. Add to the fennel.
Make the salad dressing by mixing the orange juice from half the orange, the lemon juice, an equal amount of olive oil and salt and freshly ground black pepper.
Drizzle over the fennel and orange and serve.