Bring a medium pot of salted water to a boil. Add the broccoli and blanch until tender, 2 minutes. Remove with a slotted spoon and place in an ice bath. Drain and pat dry.
Return the water to a boil, add the carrots, and blanch until tender, 2 minutes. Remove with a slotted spoon and place in an ice bath. Drain and pat dry.
Place 1 large lettuce leaf on each of 4 salad plates and arrange 1/4 cup of the chopped lettuce in the center of the lettuce leaf. Chop 1/4 of the broccoli and arrange equal amounts inside each lettuce leaf. Arrange the remaining broccoli flowerets and the carrots in each of the lettuce leaves. Cut each beet slice into 4 sticks and arrange inside the lettuce leaves, alternating with the tomato wedges. Drizzle each salad with 2 tablespoons of the dressing and serve immediately.
Combine all of the ingredients except the vinegar in a medium bowl and whisk well to blend. Whisking, slowly add the vinegar until emulsified.
Transfer to an airtight container and refrigerate until ready to use. (The dressing will keep refrigerated in an airtight container for up to 1 week.)
Yield: about 1/2 cup