For the crisps, place the vegetable oil into a deep, heavy-bottomed saucepan and heat until a small cube of bread sizzles and turns golden in 30 seconds when dropped into it. (CAUTION: hot oil can be dangerous. Do not leave unattended.) Add the tortilla pieces and deep fry for three minutes or until crisp. Carefully remove the crisps with a slotted spoon and drain on kitchen paper. Pile into a large bowl and sprinkle with sea salt.
For the dip, heat the oil in a small pan, add the onion and fry for two minutes. Add the garlic and chilli flakes and fry for one minute. Add the tomatoes and beans and fry for 2-3 minutes. Pour into a food processor and blend until smooth. Spoon into a small bowl and serve with the tortilla chips.
