Remove the racks and shelves from the oven and place them in the bath on an old towel or tea towel to prevent scratches. Fill the bath with hot water, dish soap, and soda crystals, and let them soak while you clean the oven.
Combine dish soap and bicarbonate of soda, then apply the mixture to the glass door, base, and sides of the oven. Allow it to sit for about 20 minutes, then spray white vinegar over the surfaces. You'll notice the grease starting to dissolve.
Wipe down all surfaces thoroughly. Place an oven-safe dish filled with water and a splash of white vinegar inside the oven. If you have a lemon, you can use that instead.
Set the oven to its highest temperature for 30 minutes, then turn it off and keep the door closed for another 30 minutes to let the steam work its magic.
Check on the soaking oven racks. The grease should come off more easily now. Use a wire wool sponge for any stubborn baked-on residue, then rinse everything well with the shower.
After the oven has cooled for 30 minutes, carefully open the door and take out the hot dish of water. Wipe the entire inside of the oven again with clean kitchen roll, as the steam will have loosened any remaining grime.
Reinsert the clean racks, and finish by spritzing neat white vinegar on the outside of the oven. Buff the glass and stainless steel until they shine.
