Preheat the oven to 425 degrees F (220 degrees C).
Rinse quinoa and add it to a medium-small pot with ½ tsp salt and vegetable stock over high heat. Once the liquid boils, turn heat to low, put a lid on, and cook until the water is absorbed, about 13-15 minutes. Remove from the stove and allow to rest with a lid on for 10 minutes. Allow to cool.
Meanwhile, remove the woody base of the asparagus stalks, slice the halloumi into ½ inch thick slices and cut ½ a lemon into thin slices. Reserve the remaining lemon.
Mix the juice of the remaining ½ lemon, honey, olive oil, thyme/rosemary, 1 tsp water and onion powder.
Place asparagus, cherry tomatoes and halloumi in a baking sheet and drizzle the lemony seasoning. Generously season with salt and pepper. Toss a little to coat more evenly. On top of the veggies lay the thin slices of lemon.
Bake for 15-20 minutes or until the tomatoes have burst and their skin is wrinkled. Then put the top grill or broiler of the oven at the highest temp, place the baking sheet on the highest rack of the oven, and allow the veggies and halloumi to get golden brown for about 1-2 minutes.
Serve with a side of quinoa, scraping the sauce and bits and pieces remaining in the baking sheet on top of the veggies.