1 large yellow onion, very thinly sliced (about 4 cups) 2 tablespoons malt vinegar 1 large red bell pepper, sliced into 1/4-inch strips 8 oz cremini mushrooms, stemmed and thinly sliced (about 2 cups) 2 (4oz) bonesless, skinless chicken breasts, sliced into about 1/8-1/4 inch pieces 1/4 teaspoon fresh ground black pepper 2 oz low-fat cheddar cheese, grated (about 1/2 cup) 1/4 cup 1% milk 4 large whole-wheat or multigrain wraps (about 12 inches in diameter)

1. Heat a large saute pan on high. When skillet is hot, add onion and stir constantly for 2 minutes, until onion begins to soften and release a bit of liquid. Reduce heat to medium-high and cook onion for 2 more minutes without stirring.
2. Add vinegar and 1/4 cup water, a bit at a time, stirring and scraping any brown bits from bottom of skillet as liquid evaporates. Reduce heat to low and let onion simmer for 30 minutes, stirring occasionally, until very soft, sweet and golden.
3. Meanwhile, heat a separate large saute pan on high. Add red pepper and mushrooms to hot, dry pan and saute for 2 minutes, stirring constantly as vegetables soften and release some liquid. Reduce heat to medium-low and let vegetables simmer for 5 more minutes, until very soft and most of liquid has evaporated.
4. Increase heat to high and add chicken to pan. Saute for 5-7 minutes, stirring often, until chicken is cooked all the way through. Season with black pepper, cover pan and reduce heat to very low to keep mixture warm.
5. When onions are very soft, add cheese and milk to skillet, stirring as cheese melts into onion.
6. Place a quarter of chieck mixture and quarter of onions in a line on bottom third of each wrap, leaving about 2 inches empty on each end. Roll the bottom end over mixture, squeezing gently around filling. Continue to roll up the rest of the wrap. If any filling spills out as you roll, simply add it back in through the ends.
7. Place wrap on a hot panini press, seam-side-down. Press wrap for 2 minutes or according to manufacturer directions to toast. Alternatively, position wrap on a hot grill pan on medium-high heat. Set a small, heavy saucepan on top of wrap to press it down gently and grill for 2 minutes, until grill marks are visible and wrap is crisp and toasted. Carefully turn wrap over and repeat on opposite side.
8. Move pressed wrap to a cutting board. Starting 2 inches from 1 end, cut wrap diagonally toward other end, creating a triangular piece. Reposition knife and cut again, starting at the top of the last cut and down toward tohe other end of the wrap. Continue cutting in this manner until you are left with 4 or 5 triangles.