Saute the onions in the oil until translucent, then let cool before you add it to the turkey
Combine the ground turkey with the onions, mustard and all the seasoning. I use my hands to mix everything together
Shape into four patties and I poke a hole about half way through in the middle to prevent shrinkage
Put on grill, skillet or griddle and cook through, flipping 1/2 way through cooking time. About 5 minutes per side or until internal temperature is 165 degrees. You want a turkey burger to be cook completely through