In a small bowl, mix together the ground coriander, ground cumin, salt, and black pepper. Rub the spice mixture evenly over both sides of the sirloin steaks.

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Once the oil is hot, add the seasoned sirloin steaks to the skillet.

Cook the steaks for about 4-5 minutes on each side for medium-rare, or until desired doneness. Remove the steaks from the skillet and let them rest for 5 minutes before slicing.

While the steaks are resting, char the red bell peppers by placing them directly over a gas burner or under a broiler until the skin is blackened and blistered. Turn occasionally to char all sides.

Once charred, place the peppers in a bowl and cover with plastic wrap for about 10 minutes. This will steam the peppers and make the skin easier to remove.

After 10 minutes, peel off the skin, remove the seeds, and chop the flesh. In a food processor, combine the chopped red peppers, toasted walnuts, garlic, parsley, and Parmesan cheese. Pulse until combined.

With the processor running, slowly drizzle in the olive oil until the pesto reaches your desired consistency. Season with salt and pepper to taste.

Slice the rested sirloin steaks against the grain and arrange on serving plates. Spoon the charred red pepper and walnut pesto over the sliced sirloin. Serve warm and enjoy!