Rinse red and yellow lentils thoroughly under cold water. Combine in a pot or Instant Pot with water, chopped tomato, and salt. Add fenugreek leaves if using. Pressure cook for 7 mins and allow natural release for 10 mins, or simmer for 20 mins until tender.

In a spice grinder, crush cumin seeds and black peppercorns, then set aside for tempering.

In a skillet, heat 2 tbsp of oil over medium heat. Add half of the crushed spices and sizzle briefly. Add chopped onion and sauté until translucent, about 5-7 mins. Stir in garlic, ginger, and chili; cook until golden brown, about 2-4 mins. Add garam masala and curry leaves, cooking for 30 seconds.

Gently fold the caramelized onion mixture into cooked lentils. Heat through for 5 mins.

Heat 2 tbsp of oil, add remaining spices, and toast until fragrant. Pour the hot tempering over the dal before serving.

Garnish with chopped cilantro and lemon juice if desired to add freshness.

Store leftovers in an airtight container; refrigerate for up to 3 days or freeze for a month.