How do I make bhindi not slimy?

Dry it fully before cutting, fry it uncovered in hot oil until the threads disappear, add salt only with the masala, and finish with something sour like lemon.

Can I make bhindi without onion?

Yes. Fry it with cumin, green chillies and dry spices only for a simple bhindi fry, but the onion version is the one most Pakistani homes make.

Bhindi Masala Recipe (Pakistani, Step by Step)

Name: Bhindi Masala
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: Pakistani
Ingredients: ½ kg Okra (bhindi), tender, washed, dried and cut into 2 cm pieces; ⅓ cup Cooking oil; ½ tsp Cumin seeds (zeera); 2 medium onions Onions, sliced; 1 tsp Ginger-garlic paste; 1 medium tomato Tomatoes, chopped; 3 Green chillies, slit; 1 tsp Salt, adjust to taste; 1 tsp Red chilli powder; ¼ tsp Turmeric (haldi); 1 tsp Coriander powder; ½ tsp Dried mango powder (amchur); 1 tbsp Lemon (lemon juice)

Method

Wash the okra whole, then spread it on a cloth and let it dry completely, or pat each one dry. Top and tail them and cut into 2 cm pieces.
⏱ 15 min
Heat 4 tablespoons of the oil in a wide pan on medium-high heat. Add the okra in a single layer and fry, turning now and then and without covering, until the sticky threads disappear and the edges brown. Lift out onto a plate.
⏱ 10 min
Add the remaining oil to the pan. Add the cumin, then the onions, and fry on medium heat until soft and just turning golden.
⏱ 6 min
Add the ginger-garlic paste, tomato, green chillies, salt, red chilli, turmeric and coriander powder. Fry until the tomato breaks down and the oil separates.
⏱ 4 min
Return the okra to the pan with the amchur, if using. Toss gently and cook uncovered on low heat until the okra is tender.
⏱ 6 min
Squeeze over the lemon juice, toss once more and serve.