Place a grill pan over medium-high heat and heat for 5 minutes.
Meanwhile, put the tomatillos, onion, jalapeño and poblano in a large mixing bowl. Drizzle with 3 tablespoons of the vegetable oil, sprinkle generously with salt and toss to evenly coat the vegetables. Brush the hot grill with the remaining tablespoon vegetable oil.
Grill the vegetables, turning occasionally, until charred and softened, 12 to 15 minutes. Transfer the tomatillos and onions to the bowl of a food processor. Transfer the peppers to a cutting board to cool briefly. Trim the stems off the peppers and remove the seeds if you don't want it too spicy. Add the peppers to the food processor.
Add the garlic and lime juice to the food processor and pulse until the vegetables form a thick paste, about 2 minutes. With the processor on, slowly drizzle in the olive oil. Turn off the machine, add the cilantro, sugar and 1 teaspoon salt and pulse until smooth. Remove all but 1 cup of the salsa from the food processor. Set this green salsa aside.
To the remaining 1 cup salsa in the food processor, add the can of tomatoes. Pulse for 1 minute more until a smooth red salsa is formed. Serve both salsas with tortilla chips.