1. Preheat the oven to 180 C / 380 F
2. Wash and pat dry all the vegetables
3. Trim the end off each of the asparagus spears – either snap or cut off the dry section
4. Trim the end off the zucchini, cut lengthwise into halves and then each half into thirds
5. Cut the bell peppers in half and remove the seeds, cut into long finger-width strips
6. Cut the large portobello cap into 1/3 inch (a bit less than 1 cm) widths – set aside
7. Put all but the mushrooms into an elongated bowl
8. Pour the oil onto the vegetables and toss to coat well
9. Sprinkle on the garlic powder and toss
10. Add half of the turmeric and toss. Reserve 1 tbsp for the mushrooms, but sprinkle the rest onto the vegetables and toss again. Do in two batches to get better distribution of the turmeric.
11. Place seasoned vegetables onto a baking sheet, set aside while preparing the mushrooms
12. To the mixing bowl you used to season the other vegetables add 1 tbsp of melted butter and the reserved tablespoon of turmeric powder. Blend.
13. One at a time, dip each slice of portobello mushroom and place on top of the other vegetables
14. Place in the middle position of the oven and roast for 8 minutes or until al dente, or a couple of minutes more for softer vegetables. Enjoy!