Heat the olive oil and the butter in a medium, nonstick skillet, over medium-high heat. Add the sausage and cook, stirring constantly to break up into bite-size pieces. When the sausage is brown (no pink should be left), add the green bell peppers and cook, stirring, for 1 minute.
Add the eggs and cook, stirring constantly with a wooden spoon, until the eggs are just set, about 30 seconds. Sprinkle with the cheese, remove the skillet from the heat, and let rest for 20 to 30 seconds until the cheese melts.
Spoon half of the filling down the center of each tortilla. Roll up the tortilla, burrito-style and place seam side down on a plate to keep the burrito closed. Top with salsa and garnish with sliced green onions, if desired.
Yield: about 3/4 cup