1. Place peas or beans in a medium saucepan with 3 cups of water and chili flakes; bring to a boil, reduce heat and simmer 10 minutes, or until beans are tender. Remove from heat, and cool slightly, retaining cooking liquid.
2. Place bean mixture in a blender; pulse until beans are crushed but not pureed. Stir in cumin and 1 teaspoon of oregano. Transfer to bowl and set aside.
3. Preheat oven to 350°.
4. Place chicken breasts in a heatproof skillet. Drizzle lemon juice and broth over chicken. Sprinkle with remaining oregano. Cover pan and bake at 350° for 30 to 35 minutes, or until juices run clear. Cool slightly; cut into thin strips or shred by hand.
5. Turn oven down to 200°. Wrap tortillas with foil and place on baking sheet; bake for 15 minutes, or until warm and steamy.
6. Assemble tacos: Spread each tortilla with black eyed pea puree, shredded lettuce, diced tomato, and diced onion. Add strips of chicken, sprinkle with cheese, and serve.