As my garden is not as sunny or as warm as it could be for growing a really bountiful harvest, I have to look to using all parts of the vegetables that I can grow.
When I harvest turnips for dinner, I cook the root and greens. I pull the leaves off of the tough and fibrous stems and use them as cooked greens. But I don't discard those stems. I cut them into 1-inch lengths and simmer in a saucepan full of water for an hour. It's important to cut the fibrous stems into short, 1-inch lengths so the "stings" don't tangle on the blade of the blender. Ask me how I know. . .
After cooking, I use my immersion blender to puree the liquid and stems, then strain it all through a mesh sieve. At this point, I compost what doesn't pass through the sieve. What remains is a stock with a mild turnip flavor -- great as a basis for an all vegetable soup.
To make a pot of soup using the turnip stock, I add 1 large diced carrot, some onion powder, garlic powder, salt, and black pepper. I then allow it all to simmer until the carrot is soft. I add instant mashed potatoes to thicken the soup and to moderate any turnip-iness and adjust the flavor by adding more salt, garlic, powder, and or onion powder.
I like this soup topped with cheddar cheese. One of my daughters likes to swirl in a pat of butter. It's also tasty topped with plain yogurt or sour cream.
This technique is also a great use for the fibrous stems of mature kale, whether from the market or garden grown. No need to throw those out. They make a delicious broth to use as the basis for a broccoli and potato soup.
My garden motto -- use every bit of the vegetable when possible.