The Luberon is one of the best areas in France to eat. The local ingredients — truffles, lavender honey, cherries, almonds, olive oil, and wine — are exceptional, and the restaurant scene has been driven upmarket by the influx of well-heeled second-home owners over the past thirty years.
The village restaurants range from good bistros serving simple Provençal cooking (lamb, ratatouille, aïoli, goat's cheese) to serious gastronomic establishments. Lourmarin has several excellent options clustered around the main street. Bonnieux has a terrace restaurant with views across the valley that is better than it needs to be. In July and August, book everything ahead — the best tables fill days in advance.
Markets are as important as restaurants here. The Saturday market in Apt, the Tuesday market in Apt again, and the various smaller village markets provide everything you'd need for a picnic better than most restaurants could serve.