How to Make It
Boil the potatoes in salted water until just tender, about 5 minutes. Remove the potatoes with a slotted spoon. Add the cauliflower and cook until crisp-tender, about 5 minutes; drain.
In a large nonreactive skillet, melt the butter in the oil over moderate heat. Add the onion and garlic and cook until soft, about 2 minutes. Add the curry powder and cook, stirring, for 2 minutes. Add the potatoes and cauliflower and cook, stirring occasionally, for 2 minutes longer.
Add the lemon juice, 1/2 teaspoon salt and 1 cup of water. Cook, scraping up the bottom, until the liquid is absorbed, about 5 minutes; serve.