Steam sweet potatoes in covered saucepan until tender and set aside.
In a large pot, cook onions, garlic, jalapeno in oil until soft (about 10 minutes).
Add garam masala and cumin to the onion mixture, and add cooked sweet potatoes.
Combine sweet potatoes, onion mixture and beans. Chunky texture is fine, but If you prefer a smooth consistency, you can blend with immersion blender or food processor.
Add lemon juice, cilantro and salt to taste.
Lightly oil a 9 x 13 pyrex, place about ¾ cup of filling to each tortilla and roll into burrito. Place each burrito in pyrex. Cover with salsa and sprinkle with cheese if desired.
Bake for 25-30 minutes.