Fill a large pot with lightly salted water and bring to a rolling boil; add 2 teaspoons cumin to boiling water. Cook cauliflower florets, working in batches, in boiling water until cooked but still crisp, 1 to 2 minutes. Remove with a slotted spoon and cool on a plate.
Blend flour, egg, garlic, 1 teaspoon cumin, tomato paste, and salt in a blender or food processor until batter is smooth; thin with milk as needed.
Heat oil in a deep skillet to 350 degrees F (175 degrees C).
Dip cauliflower florets in batter; fry battered cauliflower in hot oil, working in batches, until cauliflower is golden and crispy, 6 to 8 minutes. Remove with a slotted spoon and drain on a paper towel-lined plate.