Mince garlic and mix with salt. Heat oil in large saucepan. Add garlic-salt mixture and onions. Cook over medium-high heat, stirring often, until onions are brown (6-8 minutes). Reduce heat and add chicken broth and tomatoes, mashing tomatoes with a wire whisk to combine. Add tomato paste, pepper, red pepper flakes, and sugar. Stir well and bring to a boil. Reduce heat, cover, and let simmer for 1 to 1 1/2 hours, stirring occasionally. Add parsley and basil for last 5 minutes of cooking. If serving over pasta, garnish with fresh parsley sprigs.