Beef-mushroom Stir-fry

• 2 cs rice (cooked)
• 1 garlic clove
• 350 gr beef top round steaks
• 230 ml water chestnuts
• 140 gr snow peas (frozen)
• 120 gr green onions including tops
• 80 ml water
• 16 ml low sodium soy sauce
• 10 ml puritan oil
• 5 gr cornstarch