1.Line a 10 x 20cm loaf pan or terrine mould with 3 layers of baking paper, extending 5cm above the long sides. Brush top sheet with oil.
2.Process avocados and cream cheese in a food processor until smooth.
3.Add green onions, lemon juice, garlic and chilli. Process again until well combined. Season to taste.
4.Transfer mixture to prepared pan and level-off top. Press a piece of plastic wrap onto the surface and chill for at least 6 hours, or overnight.
5.Remove plastic wrap and unmould onto a platter, removing all paper.
6.Combine parsley and pistachios in a small bowl and sprinkle over the pate. Serve with olives, tomatoes and tortilla chips.
To make tortilla chips, cut 4 large tortillas into wedges and arrange on a baking tray. Brush with olive oil and bake in a moderate oven, 180°C, 8-10 minutes, until golden and crisp.Note