There’s really not a recipe for this, just suggestions for experiments.
Cut up vegetables that sound like they’d be good roasted—things like broccoli and cauliflower (in florets); coins of carrot and parsnip; quartered small potatoes with sprigs of rosemary; plugs of celery and beets.
Heat up a mixture of oil and butter in the dutch oven to the smoking point. Put in the vegetables of greatest density (if you’re mixing different types) and brown them slightly, stirring with a wooden spoon. Put on the lid and roast them, checking occasionally. They will create their own steam.
If you want to fancy things up, you can add cider and crack the lid so the vaporized water escapes and the cider essence glazes the vegetables. Soy sauce, mirin, and a little toasted sesame oil also works.
