An "instant-read" food thermometer that can improve the results of every meal you make.
If I could only have one tool for cooking, the ThermoWorks Thermapen MK4 would be it. I can't tell you how many times it has saved my butt by making sure the meal was neither over or under-cooked. Considering how much money we spend on meat and seafood, $80-100 for this tool is a great value. Nothing else I have seen gives you the same accuracy and near-instantaneous readings that this food thermometer does.
The other reason you need a high quality thermometer is, of course, food safety. Eating under-cooked foods poses many health risks. The U.S. Food and Drug Administration says that "meat, poultry, seafood, and egg products. . . must be cooked to a safe minimum internal temperature to destroy any harmful bacteria". It also publishes minimum safe temperatures, such as 165F for poultry, 160F for ground meats, and 145F for pork. The only way to be sure food is cooked to this temperature is with a high quality food thermometer.
If you read a lot of recipes, I'm sure you have seen many cooks recommend that you "cook to internal temperature, not to time". There are just way too many variables involved (outside/ambient temperature, oven temperature, food thickness and volume, food temperature at beginning of cook, etc.) for any sort of cooking time estimate to be consistently reliable.
Many of us also rely on visual cues, like piercing chicken to see if the liquid running out is clear or pink, or tactile feedback, like how jiggly the steak is vs. firm. These certainly help, but are not nearly as accurate as using a thermometer.
Accuracy: When I first bought my smoker back in 2014, I soon realized from reading various recipes that I needed a thermometer. Lots of blogs recommended the Thermapen as "the one that all the competition pitmasters use". But the price seemed too steep for me, so I bought a $20 thermometer instead. I soon realized that there was something not quite right, as my meats turned out either too rare or too well done. I tried another cheap one, then another, from brands like Weber and Oxo. Using 3 or 4 of them at once usually resulted in 3 or 4 pretty different temperature readings, so I knew something was up. I then looked online at some ways of testing thermometer accuracy using ice water and boiling water. I tried it, and discovered that while 2 of my thermometers were pretty accurate, the other 2 were complete junk.
Speed: So, I started using the 2 thermometers that were more accurate, and my results improved. I still wasn't too happy though, and here's why. Those thermometers took about 5 seconds for the reading to stabilize, which is a REALLY long time if you want to check 8 pieces of chicken in a couple of places each. All that time, you are letting heat out of the grill, and/or burning your fingers.
So, one Black Friday I treated myself to a Thermapen MK4, their latest model, on sale for $80 or so. The difference in speed vs. my old thermometers was absolutely amazing. Their website claims a 2-3 second response time, but in reality is seems almost instantaneous. ThermoWorks instructions tell you to insert the tip of the probe (where the sensor is) past the center of the meat, and then withdraw it slowly, watching the temperature as it changes so you find the coolest part of the meat. That reading changes almost instantly as you slowly withdraw the thermometer. So, you can quickly test those 8 pieces of chicken and get that grill lid closed for more cooking.
- It's extremely accurate, within ±0.7°F.
- Readings are almost instantaneous, seeming much faster than their claimed 2-3 seconds.
Other features: As you'd expect for a $100 thermometer, the Thermapen MK4 has a number of other nice features as a bonus:
- Large, easy-to-read display.
- A backlight that comes on as needed - great for grilling at night.
- The display automatically rotates so you can read it in any position.
- Auto wake-up and shut-off. I've had mine for a year and a half and the battery has never been changed.
- 3,000 hour battery life from common AAA battery.
- The probe tucks away into the body for protection.
- Waterproof (within reason)
- Extremely solid and well-built.
- 10 colors to choose from - orange makes mine very easy to find, and happens to match my motorcycles:)