Clean the mushrooms and rub with kitchen paper. Halve the mushrooms. Cut oyster mushrooms into small pieces. Clean and wash spring onions and cut into rings. Wash, clean and halve the tomatoes.
Bring the stock and condensed milk to the boil, stir in the sauce thickener, bring to the boil again. Season to taste with salt, pepper and lemon juice. Add tortellini to the sauce and let it simmer for 2-3 minutes at low heat.
Heat the oil in a pan. Sear the mushrooms in it. Add spring onions and tomatoes and fry briefly. Season to taste with salt, pepper and thyme. Fold the vegetables into the tortellini. Arrange the tortellini on plates.
Serve garnished with thyme and parsley.