Wash the dal: Put urad dal in a bowl. Add water, rub gently with your fingers. Drain and repeat 3–4 times until the water is mostly clear. Optional: soak 15–20 minutes for faster cooking.
Cook the dal: Stovetop: Add washed dal + water + salt to a pot. Bring to a boil, lower heat, cover, and simmer 20–25 minutes, stirring occasionally, until very soft and creamy. Pressure cooker: Cook with water + salt for 2–3 whistles. Let pressure release naturally. Mash lightly with the back of a spoon for extra creaminess.
Make the tempering: Heat ghee/oil in a small pan. Add cumin seeds; let them crackle. Add onion (if using) and cook until lightly golden. Add garlic, hing, and red chilies; cook 10–15 seconds.
Combine: Pour the hot tempering over the cooked dal. Stir gently. Adjust salt and water for consistency.
To serve: Serve hot with rice, roti, or chapati. Optional garnish: chopped cilantro, squeeze of lemon.