This is a play on the Provençal speciality of crudités with a warm garlic and anchovy dipping sauce. The anchoïade keeps well in a sealed jar in the refrigerator and can be reheated gently before use.
Trim the celery and peel each stalk with a vegetable peeler to remove its stringy fibres. Cut into 5cm (2in) lengths and cook in a pan of lightly salted boiling water for 10 minutes. Drain and leave to cool.
For the sauce, melt the butter and olive oil in a pan, add the garlic and herbs and cook for 1 minute, until fragrant. Add the anchovies and cook over a gentle heat for 8-10 minutes, stirring occasionally. Season lightly, then whisk in the vinegar and mustard.
Arrange the celery on a serving dish and pour over the warm anchovy and garlic sauce. Serve with chunks of rustic bread to mop up those wonderful garlicky juices.