Heat clarified butter in large pot on medium heat.
Add onions and cook till just wilted.
Add garlic, jalapeno, cumin, lentils, ginger, curry powder, salt, pepper, sugar and bay leaf. Saute for 1 to 2 minutes until fragrant.
Add the tomatoes and deglaze pan with the vinegar.
Add the chicken stock, bring to a boil and then lower to a simmer and cook until lentils are tender, stirring occasionally.
Taste and adjust seasoning with additional cumin, salt, pepper, sugar