Slice the flank steak into very thin strips against the grain to ensure maximum tenderness.
In a small bowl, whisk together the chili powder, ground cumin, sea salt, black pepper, and lime juice to create a marinade.
Toss the steak strips in the lime-spice mixture until every piece is evenly coated.
Heat 0.5 teaspoon of extra virgin olive oil in a large non-stick skillet over medium-high heat.
Add the steak strips to the skillet and sear for 2-3 minutes until browned and cooked through, then remove and set aside.
Add the remaining 0.5 teaspoon of olive oil to the same skillet and sauté the sliced bell peppers and onions for 3-4 minutes until they are tender-crisp.
Wipe the skillet clean and place the whole wheat tortilla inside over medium heat.
Sprinkle half of the shredded Monterey Jack cheese over one half of the tortilla, then layer on the cooked steak and sautéed vegetables.
Top the filling with the remaining cheese and fold the empty half of the tortilla over to close.
Cook for approximately 2 minutes per side until the tortilla is golden brown and the cheese is fully melted.
Slice the quesadilla into three wedges and garnish with fresh cilantro before serving.