1. To prepare dressing: Heat 1 tablespoon oil In a large nonstick skillet over medium-high heat. Add onions and sugar; cook, stirring constantly, until well browned, 10 to 15 minutes. Add garlic and cook for 1 minute more. Let cool to room temperature.
2. Transfer 1/4 cup of the browned onions to a blender or food processor. Add the remaining 2 tablespoons oil, vinegar, lime juice and cumin; puree until smooth. Add cilantro and pulse to blend. Season with salt and pepper; set aside.
3. To prepare salad: Preheat grill to medium-high.
4. Combine jicama with the reserved onions in a large bowl.
5. With a sharp knife, remove the skin and white pith from oranges and discard. Working over the large bowl to catch juices, cut the orange segments from their surrounding membrane, letting the segments fall into the bowl with the jicama. Squeeze the juice from the membranes into the bowl. Add bell pepper and toss gently to combine. Season with 1/8 teaspoon each salt and pepper.
6. Season both sides of tuna with the remaining 1/8 teaspoon each salt and pepper. Grill over medium-high heat until just cooked through, 4 to 5 minutes per side. Let rest for 5 minutes before cutting into thin slices. Add the tuna to the j�cama mixture.
7. Toss lettuce with the reserved dressing in a large shallow bowl. Spoon the tuna mixture into the center of the greens and serve.

• Make Ahead Tip: Cover and refrigerate the dressing and onions (Steps 1-2) for up to 8 hours.

• Note: Jicama is a round root vegetable with thin brown skin and white crunchy flesh. It has a slightly sweet and nutty flavor. To peel it, use a small, sharp knife or vegetable peeler, making sure to remove both the papery brown skin and the layer of fibrous flesh just underneath.

Per serving: 250 calories; 8 g fat ( 1 g sat , 6 g mono ); 34 mg cholesterol; 23 g carbohydrates; 1 g added sugars; 21 g protein; 7 g fiber; 245 mg sodium; 800 mg potassium.

Nutrition Bonus: Vitamin C (135% daily value), Vitamin A (105% dv), Potassium (23% dv), Folate (18% dv), Magnesium (17% dv).