Season the stew meat generously with salt & pepper. In a large, heavy pot heat the olive oil over medium-high heat. Add the butter; as soon as it melts put half of the stew meat into the pot. Brown the meat on all sides. Once it's browned, remove it from the pot using a large slotted spoon, and put it on a plate. Add the other half of the stew meat, and repeat the browning process. Once it's well browned, remove it to the same plate.
Quickly add the diced onions to the pot, and reduce the heat to medium-low. Stir them around to coat them in oil and yummy brown bits and let them soften. Add the garlic, then add the tomato paste. Stir everything around and let the tomato paste cook for 3-4 minutes.
If you're using wine, this is the time to pour it in, stirring and scraping the bottom of the pot, lifting all of the brownings and incorporating them into the liquid. Bring to a gentle bubble, and allow the wine to reduce almost completely.
Pour in the beef broth, Worcestershire, sugar, & 1/2 tsp of salt. Add the browned beef back to the pot, being sure to pour in all the delicious juices from the plate.Bring it to a boil, reduce heat to low, put the lid on the pot, and allow to simmer and stew.
After 1 1/2 - 2 hours, add the diced turnips (if you're using them). Give it a gentle stir, put the lid back on, and cook for 15 minutes. Now it's time to add the carrots. Cook 30 minutes more, until both vegetables are tender. If you're using peas or green beans, add them now; bring the stew back to a simmer.
The gravy should be significantly thickened by now. If it's too thick, you can add a little more broth or water. Give it a taste, and season with salt & pepper to your preference. Serve the stew in a bowl, pouring it next to the creamy potatoes. Make sure you pour the juices all over the potatoes - it will make life perfect. I promise.