For the oven method, refer to the notes.
Cut up your meat into 2 cm cubes, removing most of the chunky fat pieces. Dice up, onion, garlic, celery and bacon (if you are using bacon strips). Thinly slice mushrooms.
Set an all-in-one cooker to the saute setting or use a frypan. Add butter and melt. Add onion, garlic, celery. Stir for a minute and then add mushroom and continue to saute until mushrooms are tender. Then turn off.
Add flour to a zip lock or freezer bag, add diced meat and coat the meat in the flour. Add the bacon and the meat, along with the remaining flour to the sauteed ingredients in your slow cooker.
Add water, tomato paste, mixed herbs, sugar, worcestershire sauce, salt and pepper to a small bowl and combine well. Pour over the ingredients in your slow cooker.
Put on the lid and set to the low slow cook setting and cook for 6 hours.