Clean the cutting board with warm water and mild soap
Rinse and dry it completely
Lightly sand rough spots if needed
Use food-grade mineral oil or board oil
Pour a small amount of oil onto the board
Spread the oil evenly with a clean cloth or paper towel
Coat both sides and the edges
Let the oil soak in for several hours or overnight
Wipe off any excess oil
Repeat until the board stops absorbing oil
Re-oil regularly to maintain the board