Pumpkin seeds are used as a flavorful thickener in Mexican sauces. If you cant find them, simply substitute walnuts. Chayote is a smooth, pale green vegetable that can be replaced by yellow squash, if necessary.
1. To make Sauce: Toast pumpkin seeds 3 to 5 minutes in skillet over medium heat, shaking pan often.
2. Add oil to skillet. Add green onions and garlic, and sauté 2 minutes, or until soft.
3. Purée lettuce, broth, cilantro, pumpkin seeds and 1/2 cup green onion mixture in food processor until smooth. Transfer to saucepan, and simmer 15 minutes over medium heat. Stir in lime juice, and season to taste with salt and pepper.
4. To make Vegetables and Rice: Cook rice according package directions. Warm oil in skillet over medium-high heat. Add chayote and zucchini, and cook 15 minutes, stirring often, or until soft and beginning to brown. Add remaining green onion mixture, and season to taste with salt and pepper.
5. To serve: Divide rice among 6 bowls. Top with vegetables and sauce.