In a food processor, pulse onion until a puree forms. If onions get stuck and don’t process correctly, stir with a spoon, cover, and continue to pulse. Transfer onion puree to a small bowl.

In food processor, pulse jalapeño, ginger, garlic, and ½ cup water until a paste forms. Transfer to another small bowl; reserve food processor.

In a large pot over medium heat, heat oil. Toast curry powder, stirring, until very fragrant, about 1 minute. Add onion puree; season with salt. Cook, stirring occasionally, until mixture loses most of its moisture and becomes a thick paste, about 5 minutes. Add jalapeño mixture and cook, stirring occasionally, until fragrant, about 1 minute. Add tomato paste and cook, stirring frequently, until paste darkens in color, about 2 minutes more.

Return onion mixture to food processor. Add tomato puree and yogurt. Pulse until sauce is smooth. Return to pot, stir in 1 cup water, and bring to a boil. Reduce heat to low and bring to a gentle simmer.

Pat chicken dry with paper towels; season all over with salt. Add to pot, cover, and cook, stirring every 5 minutes to ensure nothing sticks to bottom of pot, until an instant-read thermometer inserted into thickest part of chicken registers 165°, about 20 minutes; season with salt, if needed. Sprinkle with garam masala and stir to combine.

Divide rice among bowls. Spoon chicken curry over. Top with cilantro.