Combine 4 cups boiling water and bouillon cube in a saucepan until dissolved; add lentils and cook over medium heat until lentils are tender, about 30 minutes. Remove saucepan from heat and let stand for 10 minutes. Drain excess water.
Put bulgur in a heat-proof bowl; pour in 2 cups boiling water. Let mixture stand until bulgur has absorbed most of the water and is tender, about 10 minutes. Drain excess water.
Combine lentils, bulgur, onion, and parsley in a large bowl.
Mix chicken broth, red wine vinegar, cider vinegar, mustard, olive oil, garlic, oregano, Worcestershire sauce, basil, cumin, salt, hot sauce, and black pepper in a jar. Cover jar with tight-fitting lid and shake until dressing is well-mixed. Pour dressing over lentil mixture and mix well; top with scallions.