If rice hasn't already been cooked, get it started first.
Place a heavy skillet over medium heat. Add first amount of oil. Add chopped onion and cook, stirring for a minute or two. Add the ground beef and taco seasoning. Cook, stirring occasionally, until meat is all brown with no pink remaining.
Drain and rinse the beans. Warm them in a saucepan over medium-low heat with just a little water to keep them from sticking.
Place another heavy skillet over medium high heat. Add second amount of oil. Add sliced peppers. Let them char a little before stirring. Once they've nicely charred in a few places, remove them from the heat.
Slice the avocado and drizzle lime juice over the slices.
Assemble the burritos by spreading a little of each filling ingredient in a line across the centre of each tortilla. Be careful not to use too much, or they will be difficult to wrap.
Fold one side of a tortilla over the line of filling. Turn up the bottom. Fold over the opposite, and hold the burrito in your hands to eat it.
Burritos are great for customizing. If you let each person assemble their own, they can include the ingredients of their choice.