I am not a Dr. and because I do not have your complete medical history I can only provide general information and not personal recommendations. Any suggestions should be cleared by your physician or personal dietitian.
Some research shows positive benefits with a lower sodium diet along with spironolactone...however instead of using a medication, I'd recommend choosing a diet that helps using the same effects/benefits (high potassium or acts as a diuretic) to balance the sodium/potassium ratio.
Foods to eat include all leafy greens like kale, spinach, romaine and chard, beets, beans, avocado, strawberries, kiwi, tomatoes, papaya, raspberries, oranges, bell peppers, cooked sweet potatoes.
In addition, foods with a diuretic effect (cucumber, lemon, celery, beets, cabbage, parsley, tomato, watermelon, asparagus) have been shown to help lower blood pressure.
Again, please check in with your Dr. as your situation may require alternative treatments.