slice up your onion and sweat the onions with a little olive oil and salt and pepper.
while the onions are sweating, cut up an uncooked sausage of your choice, really thin. Also cut thin the tomato.
when the onions are finished pull the onions out and put them in your microwave to keep warm. Put your thin sliced sausage in the pan just long enough to heat it through, not crispy.
the sausage is just warm, open your bun put your spicy brown mustard on it, mayo, 1st goes the onions, next the sausage, next the tomaotes, put guacamole on it, then lettuce of your choice. put the top on and eat!!!