If using frozen spinach, thaw it completely and squeeze out all excess water. Chop the spinach and squeeze out any leftover water to avoid a watery bhaji.

In a wok or large pan, heat ghee or vegetable oil over medium heat.

Add cumin seed, fenugreek seeds, and black mustard seeds to the hot oil. Cook until the seeds start to pop, releasing their aroma.

Add finely sliced onion, minced garlic cloves, grated gingerroot, and optionally, finely chopped fresh chili pepper to the wok.

Sauté the mixture until the onion turns golden brown, but avoid burning or darkening it too much.

Add the chopped spinach, skinned and chopped tomatoes, and salt to the wok.

Toss all the ingredients together, ensuring the spinach is well coated with the spices and other vegetables.

Cook until the spinach wilts completely and the tomatoes soften, about five minutes. Stir occasionally to prevent sticking.

Squeeze fresh lemon juice over the bhaji and stir it through to taste, adding a tangy flavor.

Serve the spinach and onion bhaji hot with rice, roti, or as a side dish alongside your favorite curry.