Add the vegetable oil to a small saucepan and heat over medium low heat.
When the oil starts to ripple, add the garlic cloves and cook until they start to brown.
Remove the garlic cloves and leave 1 teaspoon of the oil in the pan.
Add the garam masala, coriander, cumin, fenugreek and turmeric to the oil. Mix well and cook over low heat to cook the spices and until they turn into a paste until fragrant. If the paste is too thick add more oil.
Transfer to a bowl to cool.
To a small mixing bowl add the mayonnaise, Greek yogurt, coconut milk, lime juice, salt, pepper and cooled curry paste. Mix well and refrigerate.
Bring a large pan of water to a boil.
Add the potatoes and cook for 25-30 minutes. When a knife is inserted it should go in easily then they are done.
Drain the potatoes and allow to cool.
Preheat an indoor or outdoor grill.
Cut the potatoes into wedges.
Grill the potatoes on the flesh side, about 4 minutes per side until you get good grill marks.
Serve with the curry aioli.