For a 50-calorie meal utilizing beef as the primary ingredient, here's a recommendation:

**Breakfast**

- Beef Broth Soup (made with 10g of Beef and excess water): 50 Calories

    Beef Broth Soup portion size: 200g 
    Calories in Beef Broth Soup: 50 cal

    Total Calories for Breakfast equal 50 Calories.

Grand Total Calories for the entire meal = 50 Calories,

    Nutritional Breakdown:
    - Fat: 2g (18% of total calories)
    - Carbohydrates: 0g (0% of total calories). Please add a slice of low-calorie bread (not exceeding the calorie target) for necessary carbohydrates.
    - Protein: 6g (48% of total calories)

This plan comprises of a Beef Broth Soup providing healthy and lean protein that is low in calories. You can add a slice of low-calorie bread if you need carbohydrates to start your day while not exceeding your calorie target. As this is a significantly low caloric intake, it is important to monitor your energy levels and engage in only light activities. 

