| 1 | Preheat the broiler to medium high. |
| For the pesto: |
| 1 | into your food processor or blender, place the basil, sundried tomatoes, oil and the nuts. Process until nearly smooth, check for seasoning and add salt if desired here. |
| For the sandwiches: |
| 1 | Wash the portabellas and remove the stems (save for a future use like a stew or stuffing?). |
| 2 | Slice the onions into rings. Slice the cheese. |
| 3 | Broil the mushrooms until slightly golden (about 4 minutes) and turn over for same amount of time. Remove from heat. |
| 4 | Spread the pesto evenly among the buns. Divide the cheese and the onions into four servings, and place on the buns. Put one Portabella mushroom on each bun and serve. |
