Preheat Grill. In a large bowl add bell pepper, Poblano, onion, corn and potato slices. Rub potatoes and vegetables with 3 tablespoons of olive oil. Season with salt and pepper.
On the hottest part of the grill char peppers and grill onions on all sides about 10 minutes. Once charred, transfer the peppers to a small bowl and cover with plastic wrap. Remove onions and let them cool.
Add corn and arrange potatoes in one flat layer on the grill. Grill turning often, 10-15 minutes or until tender. Remove and let them cool. Cut the corn off the cob and chop onions. When cool enough to handle, peel the peppers, remove the seeds and then chop.
ln a large bowl whisk 1/2 cup olive oil, vinegar, and thyme together. Add grilled vegetables, potatoes and all other remaining ingredients. Season and gently toss until evenly coated.