Toast the walnut halves in a dry skillet over medium heat for 3 minutes, stirring often, until they smell nutty and darken slightly; tip onto a plate to cool.

Whisk the olive oil, white wine vinegar, Dijon mustard, honey and salt in a small bowl until the dressing looks smooth and slightly thickened.

Pile the mixed greens onto a wide serving platter.

Scatter the halved grapes, toasted walnuts, crumbled Gorgonzola and sliced celery over the greens.

Drizzle the dressing over the top just before serving.

Toss gently at the table with salad servers so the grapes stay whole and the cheese doesn't turn to paste.