Fire up your grill for indirect cooking, around 300-350 degrees F. These will take about 30 minutes, but maybe as long as an hour to cook depending on your grill temperature.
Cut the onions into 1/2" rings.
Push out the inner rings, leaving the last two outer rings still together as one. Do not separate them.
Squeeze some Sriracha into a bowl that's just big enough to fit an onion ring.
Place the ring into the sauce. Using your fingers, spread the sauce all over the ring. Flip the onion and repeat. Get it coated, but not drenched.
Wrap bacon around the rings. Don't wrap too tightly since the bacon will shrink. Don't wrap it too loose or it'll fall off.
Brush (or just use your fingers) more Sriracha on the outside of the bacon.
Place the rings on your grill over indirect heat.
Grill the rings until the bacon just starts to crisp. Gently flip them (I used a grill spatula) and cook another 10-15 minutes. Remove to a baking sheet and let firm up a bit.
Serve with dipping sauce.