Preheat your grill to a medium high heat.
Prep you avocados by cutting them in half and removing the pits. Brush generously with olive oil.
Grab a grill safe pan, I have a cast iron pan I use for my grill only. Pop the butter in the pan. Toss your onions and shallots inside.
Carefully bring your pan of onions and shallots, and also your oil brushed avocados to the hot grill.
Place the pan on first. Allow to cook for about 3 to 5 minutes. You want them to soften and start to brown.
Now pop you avocados on the grill cut side down. Leave them there for about 1 to 2 minutes. You want them to char just a bit.
Carefully remove your hot pan and your avocados off the grill. Turn your grill off.
Take your avocado tool and carefully scrape out the inside. Discard the outside.
Mash the avocado gently with a fork.
If your onions and shallots have excess oil you can drain them. If not you can transfer them to the bowl with mashed avocados.
Toss in the rest of the ingredients and mix gently.
Serve immediately if possible. If not serving immediately you should keep the tomato out till you are ready to serve, cover with plastic wrap, making sure the plastic is pressed right against the guacamole. Guacamole discolours quickly if not wrapped properly.
Serve with a big old game day smile!