In a blender, combine the garlic, cumin, coriander, cardamom, cinnamon, fenugreek, paprika, nutmeg, black pepper, sriracha, and 2 tablespoons of water. Blend to combine well. Add this paste to the onions in the skillet. Cook until fragrant, about 2 minutes. Stir in the tomatoes and salt, and cook until the tomatoes are tender, about 8 minutes. Mash the larger tomato pieces.