Seed, core, and cut the peppers into 1-inch pieces. On a rimmed baking sheet toss together peppers in 1 tablespoon of the olive oil and salt and pepper, spread them out, and roast the peppers for 10 minutes until tender and lightly browned.
Meanwhile, chop the chard by slicing off the stems and roughly chopping the greens. Rinse well in a colander, then shake the colander to get rid of excess moisture.
Heat a large pot over medium high heat. Add the 1 tablespoon of olive oil, then add the onions and saute for 4 minutes. Then add the garlic, and stir for another minute. Add the chard, season with salt and pepper and saute for about 5 minutes, until the chard is tender.
Place the couscous in a mixing bowl. Add the remaining 1 tablespoon of olive oil and lemon juice and toss to combine. Add the cooked peppers and chard, toss to combine everything well, and check for seasonings.
To make the Israeli couscous, use 2 1/3 cups vegetable broth or water to 1½ cups Israeli couscous. Heat 2 teaspoons of olive oil in a medium pot over medium high heat. When the oil is hot, add the couscous, and stir in it the oil occasionally for about 3 minutes, until it starts to color. Add the broth or water, cover the pot, and bring to a simmer. Lower the heat and continue to simmer for about 12 minutes, until the liquid is mostly absorbed, and then turn off the heat and let sit covered for another 2 minutes.