Mix 750 ml (3 cups) of lukewarm water with 250 ml (1 cup) of white vinegar and pour this solution into a 1-litre spray bottle. Apply with a sponge, then wipe with a cloth.
Heat a cup of water with a tablespoon of lemon juice for 2-3 minutes at maximum power. This releases a lot of steam which will settle on the walls of the oven. Just wipe with a sponge. No need to rinse, lemon removes grease and it perfumes.
Dilute 50 g (1/3 cup) of baking soda in one litre of water. Apply this solution with a sponge. To remove stubborn stains, sprinkle some baking soda directly on your sponge. Since the powder is very fine, it will scrub without scratching. No need to rinse.
Mix 50 g (1/3 cup) of baking soda with 2 tablespoons of water to make a paste. Apply this paste on the walls and greasy surfaces of your oven. Leave on overnight (12 hours). The next day, rinse and rub with a wet sponge. If there are still any stains left, reapply the paste and add (pure) white vinegar to it. Heat for 30 minutes at 175°C/350°F, then wipe with a damp sponge.
Rub the dry sink with a cloth and flour: Surprising result.
And what tricks did your grandma hide up her sleeve? Would you like to share them?