Minted Pasta and Fruit Salad

8 oz. rotini, bowties, or small shells, uncooked
4 pears, seeded, cored, and diced
2 tsp. lemon juice
2 cups seedless red grapes, cut in half
2 navel oranges, peeled, sliced, and quartered
4 oz. feta cheese, crumbled
1 tbsp. fresh oregano, chopped
2 tbsp. fresh mint, chopped
1 tbsp. white wine vinegar
3 tbsp. orange juice
2 tbsp. vegetable oil
1⁄2 tsp. freshly ground black pepper
1⁄2 head romaine lettuce, torn into bite-size pieces