Ingredients

1/2 cup dried French green lentils, rinsed, drained, and picked over

1 small red onion, halved

3 tablespoons red-wine vinegar

3/4 teaspoon Dijon mustard

1/4 cup plus 2 tablespoons extra-virgin olive oil

Coarse salt and freshly ground pepper

4 ounces baby arugula (6 cups loosely packed)

12 ounces cherry tomatoes, halved if large

3 ounces goat cheese, crumbled

Preparation

Place lentils and 1 onion half in a medium saucepan; cover with cold water by 2 inches. Bring to a boil. Reduce heat, and simmer, partially covered, stirring occasionally, until lentils are tender, about 20 minutes. Drain; discard onion half. Transfer lentils to a medium bowl.

Chop remaining onion. Combine vinegar and mustard. Pour in oil in a slow, steady stream, whisking constantly until emulsified. Add chopped onion. Season with salt and pepper. Toss lentils with half the vinaigrette; let cool.

Arrange half the arugula on a platter. Spoon half the lentils on top. Top with half the tomatoes and half the goat cheese. Repeat with remaining ingredients to form another layer; drizzle with remaining vinaigrette.