Add water, salt, sugar, sliced onion, garlic cloves, and juice of 1/2 lemon in a large sauce pan over medium heat. Bring to a simmer and cook 3-5 minutes, until sugar is dissolved. Remove from heat and let the brine cool completely (about 30 minutes).
Meanwhile, cut each chicken tender into 3-4 bite sized pieces (depending on their size).
Add the chicken nuggets and cooled brine to a Ziploc bag or large container. Press out the excess air from the Ziploc bag before sealing (or make sure the chicken is completely submerged in brine in container before covering with lid).
Refrigerate for 8-24 hours. *Important Note: Do not brine chicken for longer than 24 hours.
Using a colander, drain brine from the nuggets, then rinse nuggets with cool water. Use paper towels or a clean kitchen towel to pat chicken completely dry before seasoning.
Oil the grill grates (or perforated grilling pan) to prevent sticking. Preheat the grill to 350ºF.
Mix the paprika parsley, kosher salt, garlic powder, and onion powder together in a small bowl.
Place chicken on a baking sheet or perforated grilling pan, brush with oil and season on both sides.
Using indirect heat, grill the chicken for 5-6 minutes, then flip nuggets over and cook another 5-6 minutes. Check the internal temperature of a couple of grilled nuggets to ensure it is 165ºF before removing them from the grill.
Notes
The brine can be prepared and refrigerated for up to 7 days in advance. However, do not brine chicken for longer than 12 hours. Dispose of all brine and do not reuse it.Good Dipping Sauces for Chicken Nuggets