Add Tea Tree to the bicarb and mix it in so the powder absorbs the oil then add hot water. If your plugs get particularly dirty you can also add lemon juice.
The bicarb is an odour neutraliser and also fizzes so lots of bubbles to clean deeply. Tea tree is antibacterial, anti fungal so general beneficial to avoiding smells and build ups of bacteria too, lemon juice strips grease from things so good at getting rid of sweat etc