Break 3 heads broccoli and 1 cauliflower into florets.
Combine with 4 thinly sliced carrots.
Cook in boiling salted water until tender-crisp, from 4 to 6 min.
Whisk ⅓ cup olive oil with 2 tbsp white wine vinegar, 1 tbsp Dijon and ½ cup chopped fresh dill or ½ tsp dried dillweed.
Toss with drained vegetables.
Serve at room temperature.