- Prepare and light the barbecue or preheat a grill or griddle. Mix the olive oil with the dried herbs, then season. Peel the celeriac, trim and cut into 4 x 1cm thick rounds then brush with the flavoured oil. Cook slowly over a warm barbecue, turning often and brushing with the herby oil for 25 minutes until tender and golden.
- Meanwhile, mix the finely chopped herbs with the garlic, capers, walnuts, lemon zest and olive oil, then season. Spoon over the steaks and serve with lemon wedges.