1 cup red lentils, rinsed
2 teaspoons curry powder
1/2 teaspoon ground turmeric
1/2 teaspoon ground cumin
1/2 teaspoon chili powder
1/8 teaspoon crushed red pepper, or to taste
1 clove minced fresh garlic
1 teaspoon minced fresh ginger
1 cup tomato puree, no salt added (see note)
1 large onion, chopped