Combine water and sorghum in a small pot. Bring to a boil; reduce heat to medium-low, cover, and cook until sorghum is tender yet firm to the bite, about 1 hour. Drain any excess water and cool, about 10 minutes.
Transfer sorghum to a large bowl. Add tomatoes, celery, onion, cilantro, jalapeno, and garlic; toss to combine. Stir in Italian dressing and lemon juice. Cover bowl with plastic wrap and chill before serving, about 30 minutes.
