Wash and dry all produce. Adjust rack to middle position and preheat oven to 450 degrees. Mince or grate garlic. Trim and discard woody bottoms from asparagus, then cut into 3-inch pieces. Strip thyme leaves from stems. Discard stems; roughly chop leaves. Put stock concentrates and 1 cup water in a small pot and bring to a simmer.

Toss garlic, asparagus, tomatoes, half the thyme, and a drizzle of olive oil on a baking sheet. Season with salt and pepper. Roast in oven until asparagus is tender and tomatoes burst, about 20 minutes, tossing halfway through.

Thinly slice scallions, keeping greens and whites separate. Melt 1 TBSP butter in a medium pot over medium heat. Add scallion whites and cook, tossing, until fragrant, 1-2 minutes.

Add couscous and remaining thyme to pot with scallion whites. Cook, tossing, until grains are lightly toasted, about 1 minute.

Pour simmering stock into pot with couscous. Reduce heat to low, cover, and simmer until tender, 8-10 minutes.

Fluff couscous with a fork. Season with salt and pepper. Divide between plates, then top with roasted veggies. Sprinkle with almonds, feta cheese, and scallion greens.