Coat a large nonstick pan, pot, or Dutch oven with cooking spray. Add beef cubes to pan and cook for 5 minutes, over medium-high heat. Turn to brown on all sides. Using a slotted spoon, remove the beef from pan.
Heat 2 teaspoons of oil in same pan. Add onions and cook for about 3 minutes. Stir in garlic and continue to cook until onions are soft, about 2 more minutes. Stir often.
Add tomato paste and cook for 1 minute, stirring often.
Stir in beef stock and beer, scraping down the sides to loosen the browned bits.
Add back browned beef and stir in bay leaves, salt, and pepper. Bring to a boil, cover, reduce heat and simmer for 1 hour. Stir occasionally.
Add potatoes, sweet potatoes and bring to a boil. Turn down to a simmer, cover, and cook for an additional 40 minutes.
Stir in carrots, cover, and simmer for 30 more minutes.
In a small bowl, add cornstarch and a little water, and using a whisk or fork, slowly mix to dissolve. Add dissolved cornstarch to stew and mix well. Cook uncovered over medium-high heat until stew is thickened, about 10 minutes.
Remove bay leaves before serving.