| 3 tablespoons vegetable oil |
| 2 cups thinly sliced red onions |
| 2 cups thinly sliced yellow or white onions |
| 1/2 cup seeded and diced fresh red chili peppers |
| 8 tomatoes, each cut into 6 wedges |
| 2 pounds uncooked large shrimp, peeled, cleaned, and deveined |
| 1/2 cup chopped scallions |