TO ROAST POBLANO PEPPER:
Preheat oven to 475 degrees and line a baking sheet with foil. Place pepper on prepared baking sheet and roast for 30-40 minutes, turning every 15 minutes to ensure even roasting.
When pepper is done, place in a bowl and cover with plastic wrap. Let sit for 20-30 minutes.
Lightly rub the roasted skin between your fingers (if you have latex gloves, they come in handy here!), to peel the skin off.
Slice pepper open and remove seeds.
Dice and set aside.
TO CHAR CORN:
Add 1/2 Tbsp butter and a small drizzle of oil to a skillet and heat over MED to MED-HIGH heat. Shuck corn, if necessary, and place corn ears in the skillet. Cook, turning to char all sides, about 5-10 minutes, until golden brown marks are made.
Remove to a plate to cool for a few minutes.
Carefully slice charred kernels off the cob and set aside.
TO MAKE GUACAMOLE:
Scoop out avocados into a bowl and add cilantro, onion, lime juice and salt. Use a fork or potato masher to mash ingredients to desired texture.
Stir in chopped poblanos and corn and garnish with chopped tomatoes.