Is cooking with hydrogen peroxide an accepted practice?
The Hong Kong Centre for Food Safety offers the following information and advice:


  Use of Hydrogen Peroxide in Food Processing
  
  
  Because of its strong oxidising property, hydrogen peroxide is used as
  a bleaching agent in some foods such as wheat flour, edible oil, egg
  white etc. in countries like the US, Canada, Australia and New
  Zealand.
  It is also allowed to be used as an antimicrobial agent in food, e.g.
  milk, and as a sterilizing agent for food packaging materials.
  


and


  Safety of Hydrogen Peroxide
  
  
  Oral ingestion of 3% hydrogen peroxide solutions (household strength)
  generally does not result in severe toxicity but may result in
  vomiting, mild irritation to mucosa and burns in the mouth, throat,
  oesophagus and stomach. Ingestion of higher concentration, e.g. >10%,
  can result in more dangerous sequelae such as burns to mucus membranes
  and gut mucosa.
  Hydrogen peroxide is unstable and would decompose in contact with food
  and after cooking.
  


and, finally,


  Advice to the Trade
  
  
  If hydrogen peroxide is used in processing food, only food grade
  hydrogen peroxide should be used in processing food.
  The amount of hydrogen peroxide to be used in food processing should
  be limited to the amount sufficient for the purpose.
  Appropriate measures should be taken to remove residual hydrogen
  peroxide from the finished products.
  


Based on this information, it seems there is some precedent for using hydrogen peroxide in a cooking environment.