Add oats and mix to coat.
You can use frozen strawberries. No need to defrost before using them.
Preferably, use organic strawberries. For non organic strawberries, see how to wash them to get rid of pesticides.
Use a baking dish (casserole dish | pie dish) or a cast iron pan of about 2 liters, 1 3/4" to 2" | 4.5 to 5 cm deep.
Choose one of these baking dishes (approximate size):
1 pie dish, what I used here, 9" or 10" | 23 to 26 cm
1 square baking dish 8 x 8" or 9 x 9" | 23 x 23 cm or 25 x 25 cm
1 oval baking dish, about 12" | 30.5 cm
1 rectangular baking dish 11 x 7" | 28 x 18 cm
I use American measuring cups and spoons.