Heat a heavy bottomed skillet over medium high heat until smoking. Open a window unless you have a killer exhaust system. Preheat your grill to medium (alternatively, if you have a gas stove, you can just use the cook top)
Pat the tilapia dry and rub with a heavy coating of blackening seasoning. Melt the butter in the preheated pan. When the foam subsides, lay the fish in and let cook, undisturbed for 2 to 3 minutes. Flip and cook 2 to 3 minutes longer, until fish is cooked through, and flakes with a fork. Remove from heat and cover with foil to keep warm.
Meanwhile, brush the sliced pepper and onion with a thin coat of olive oil. Char on the grill 3 to 4 minutes per side, until strong grill marks appear. Flip and grill 3 to 4 minutes longer.
Serve the blackened tilapia over brown rice and beans with charred onions and peppers. Top with cilantro, avocado, and a touch of chipotle sauce.