Heat a large soup pot or dutch oven to medium-high. Add a couple tablespoons of oil and add the carrots, celery and onion with a good pinch of salt. Sauté for 5 minutes. Add the asparagus, thyme, garlic and tomato paste and sauté with an additional pinch of salt. for about 3 minutes more. Add the couscous, garbanzo beans, diced tomatoes and broth. Bring to a boil then turn down to a simmer. Taste the broth add salt until it is seasoned. This is a huge pot of soup and it will need lots of salt to season all the vegetables plus the broth. Simmer for 20-25 minutes, or it is reduced to your desired thickness. Add the chard and simmer for another 10 minutes. Last, add the fresh lemon juice and parsley and serve.