Spray a 6-quart heavy kettle well with non-stick cooking spray and add crushed red pepper. Heat over medium flame for 10 seconds until fragrant. Add the leeks and celery and let cook 2-3 minutes, stirring often. Add carrots, parsnips, turnips, and cabbage. Continue stirring and let cook 4-5 minutes until beginning to soften. Add garlic; cook 1 minute.
Pour in tomatoes and sprinkle with Herbes de Provence, salt, and pepper. Stir, cover, and let come to boil. Pour in stock, stir, cover, and bring to a boil again.
Reduce heat to simmer and cook until vegetables are nearly-tender, fifteen – twenty minutes. Taste and adjust seasonings. Serve hot garnished with fresh basil or pistou (pesto), if desired. (See link in post for pistou recipe.)