You can use the peppers, either raw or roasted. To roast:
Preheat broiler. Line a baking sheet with foil, leave an extended edge. Place whole peppers, in a single layer, on the foil and place baking sheet about 6" from broiler. Broil until lightly charred, using tongs to rotate peppers until all sides are charred. Draw foil around peppers and remove from oven. Close foil packet for 5 minutes or so. Once the peppers are cool enough to touch, peel peppers and discard seeds. Slice ninto 1/4" strips.
Blanch asparagus until just tender (al dente). You can do this step before or after you cut into 1" pieces. Set aside.
Make the dressing: In a large bowl, whisk together garlic, lemon juice, oregano, basil and salt& pepper. Whisk in olive oil, slowly. Taste and adjust seasoning.
Add greens to salad dressing bowl and toss, slightly. Add in garbanzo beans, pepper strips and olives, toss well. Add asparagus and toss gently. Sprinkle feta cheese on top and plate to serve.