Hello Karin. You will be glad to know that your current instinct of using cold water is actually one of the safest and most effective methods recommended by culinary professionals and food safety guidelines alike, provided a few key precautions are taken to protect the meat's texture and safety.
To defrost your minced beef and chicken fillets properly using cold water, first ensure that the meat is sealed tightly in a leak-proof plastic bag. If water enters the packaging, it will make the minced beef waterlogged and mushy, and it will degrade the texture of the chicken fillets. Place the sealed bag into a large bowl and completely submerge it in cold tap water. It is very important that the water is strictly cold, not warm or hot, because warm water allows the outer surface of the meat to enter the temperature danger zone where bacteria multiply rapidly while the inside is still frozen. Change the water every 20 to 30 minutes so it stays cold and continues conducting heat efficiently. A standard pack of minced meat or chicken fillets should thaw evenly in about 30 to 45 minutes.
If you are pressed for time, the microwave defrost function is another safe option, though it requires extra care. Set your microwave to the defrost setting (around 30 percent power) and heat the meat in short two-minute intervals, flipping the chicken pieces or gently separating the thawing outer layers of minced beef between intervals. Be cautious, as microwaves tend to cook the outer edges before the center thaws, which can toughen the meat.
Once your meat is defrosted, cook it immediately. For the best culinary results, remember to pat the chicken fillets dry with a clean paper towel before seasoning to ensure a good sear in the pan. I hope this helps, and I wish you a wonderful dinner tonight.