Step 1

Pour water into a large saucepan or small pot to come 1" up the sides, bring to a boil, and set a bamboo steamer on top. (Or if using a metal steamer basket, set inside saucepan and add water to a depth of about 1"; basket should sit above water. Bring water to a boil.) Arrange squash across bottom of steamer, cover, and cook 8 minutes. Scatter radishes, broccolini, and carrots around and steam until everything is fork-tender, about 5 minutes.

Step 2

Meanwhile, whisk lemon juice, miso, garlic, ginger, honey, and sesame oil in a small bowl. Whisking constantly, gradually add olive oil. Whisk until emulsified; season dressing with salt and pepper.

Step 3

Divide rice between bowls, top with vegetables, and spoon as much dressing over as you like.