Rinse the mixed salad greens thoroughly under cold water. Use a salad spinner or clean kitchen towels to dry completely so the dressing adheres properly.

Halve grapes and slice onion

Wash the red and green seedless grapes, then slice each grape in half. Thinly slice the red onion into half-moons and separate into rings.

Place the dried greens in a large serving bowl. Add the halved grapes, sliced red onion, toasted walnuts, and crumbled goat cheese. Toss gently to combine just before dressing to keep textures distinct.

Make Herb-Grape Vinaigrette

Crush grapes for juice

Place the 1/2 cup fresh red grapes in a small bowl or mortar and lightly crush them with the back of a spoon or pestle to release their juice. Strain through a fine-mesh sieve into a small bowl, pressing solids to extract about 3 tablespoons of juice. Discard solids.

Emulsify dressing

In a small bowl or jar, combine the strained grape juice, extra-virgin olive oil, white wine vinegar, lemon juice, honey, and Dijon mustard. Whisk or shake vigorously until emulsified.

Stir in the chopped thyme, chiffonaded basil, salt, and freshly ground black pepper. Taste and adjust seasoning—add an extra 1/2 tsp honey if you prefer a sweeter dressing or another 1/2 tsp vinegar for more acidity.

Assemble and Serve

Just before serving, drizzle about half the vinaigrette over the prepared salad and toss gently to coat. Add more dressing to taste (reserve about 1-2 tablespoons for guests who want extra).

Transfer the salad to a serving platter or leave in the bowl. Scatter any reserved goat cheese and walnuts on top for visual appeal. If using prosciutto, arrange ribbons around the salad; if using crostini, serve on the side.

Serve immediately. Leftover dressing can be refrigerated in a sealed container for up to 3 days—bring to room temperature and whisk before using. Salad components are best when dressed just before serving to prevent sogginess.