Lightly brush one side of each tortilla with cooking oil, or spray with nonstick spray.
Divide cheese evenly among unoiled sides of two of the tortillas. Divide beans evenly among tortillas.
Top with sweet pepper strips, jalapeno slices, and pepperoncini pepper strips. Top with remaining tortillas, oiled sides up.
Heat a heavy skillet or griddle over medium heat. Cook quesadillas, one at a time, about 1 to 2 minutes per side or until cheese melts and tortillas are lightly browned.
Remove to cutting board. Cut each quesadilla into eight wedges; serve warm.
If desired, dollop with sour cream.
Please note that some ingredients and brands may not be available in every store.