Cook the red lentils if you are starting from dry lentils and haven't cooked them yet.
Heat the coconut oil in a large skillet (preferably nonstick). Add the coriander seeds and cook just until starting to turn golden, about 45 seconds. Add the ginger, garlic and jalapeno, and cook for another 60 seconds until slightly softened. Add the ground cumin, cayenne, garam masala, and turmeric, and cook for 30 seconds more until fragrant.
Stir in the salt and diced tomatoes, and reduce the heat to medium-low. Continue to cook, stirring occasionally, until the tomatoes are starting to break down and release their juices, about 10 minutes. (I use this time to prep the cilantro and scallions, and clean up from cooking the lentils).
Add the lentils to a food processor. Use a spatula to add the spice and tomato mixture, including all of the oil in the pan. Blend until smooth. Add the lemon juice and blend. Season to taste with additional salt and lemon.
Remove the mixture from the food processor. Stir in the fresh cilantro and scallions. Serve warm or chilled! Leftovers will keep in the fridge for about a week.
Notes
To substitute ground coriander for the whole seeds, use 1 teaspoon ground and add it with the other ground spices.To make the dip more spicy, add ground cayenne to taste along with the other ground spices.