Preheat oven to 425°. Combine oil with turmeric, lemon juice, and Sukhi's Madras Vegetable Mix in a large bowl; stir to combine. Add potatoes and cauliflower and stir to combine. Spread vegetables on a large shallow rimmed baking sheet (I like to line mine with parchment so the turmeric doesn't stain the sheet). Roast for 25 minutes, stirring once or twice, until vegetables are tender but not too soft.