Grease a slow cooker bowl. Combine soy sauce, tomato paste, sugar and 1/8 teaspoon pepper in a bowl.
Pieces of beef strung on two wooden skewers.
Heat oil in a frying pan. Put the kebabs, fry until golden brown on all sides. Transfer to a plate, brush with soy sauce on all sides.
Add the onion and 1/8 teaspoon of salt to the fat in a skillet and cook for 2-3 minutes. Add garlic and cook for another 30 seconds.
Add water, tomato sauce, half of ketchup and bring to a boil.
Place the metal basket upside down in the slow cooker bowl. Place beef skewers on top, brush with soy sauce and tomato paste on top. Cover and cook for 6-7 hours at medium power or 4-5 hours at maximum power.
Transfer the beef skewers to a dish, remove the meat from the skewers, cover with foil.
Remove the steamer from the slow cooker bowl. With a large spoon, remove the fat from the surface of the sauce formed during cooking.
Transfer the sauce to a saucepan, add the remaining ketchup. Bring to a boil, cook for 5 minutes. Add vinegar and hot sauce, season with salt and pepper.
When serving, pour a little sauce over the meat and serve the rest separately. BBQ beef is ready.