Lay out 2 of the flour tortillas on a flat surface. Top with 1/2 cup of the Cheddar, spreading evenly over the tortillas. Divide the steak among the tortillas and sprinkle with the desired amount of jalapeno. Top with salsa and remaining 1/4 cup cheese. Top with remaining tortillas and press to seal.
Heat a large saute pan over high heat. Add enough oil to coat the bottom of the pan and lower the heat to medium. Cook until golden brown on both sides, about 3 minutes per side. Repeat with the other quesadilla.
Let cool for 5 minutes. Slice into 8 or 10 pieces. Garnish with salsa and cilantro sprigs.