Heat oil in a large Dutch oven over medium-high heat.
Mix flour, salt, and pepper in a large bowl. Add cubed beef and toss in flour mixture to coat.
Add beef and any remaining flour mixture to pre-heated pot and cook meat until browned, stirring occasionally, about 10-12 minutes.
Add onions and water. Lower heat, cover, and simmer 1.5 hours or until meat is tender.
Add potatoes and carrots to pot. Continue to simmer until vegetables are cooked, 30-45 minutes.
Mix cornstarch and cold water with a fork until combined. Add to stew, along with dried summer savory, and stir to combine. Bring to a light boil and cook 5 minutes more to thicken.