To prepare marmalade, warm olive oil and butter in a saucepan over medium heat. Add plum, shallots, tomatoes, and garlic; bring to a simmer, and cook 30 minutes, stirring often. Stir in sugar, harissa, thyme, and vanilla bean. Simmer 20 minutes or until thick. Remove from heat; cover and let stand 30 minutes. Discard thyme sprig and vanilla bean; stir in basil and 1/4 teaspoon salt.
To prepare filling, heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add onion and potatoes to pan; sauté 5 minutes or until onion is tender. Reduce heat to low. Add carrot, curry paste, and garlic to pan; cook 5 minutes, stirring occasionally. Add 1 cup water and coconut milk; bring to a simmer. Cook 15 minutes or until liquid almost evaporates and potatoes are tender. Stir in lime juice and 1/4 teaspoon salt. Transfer to a bowl; cool. Partially mash potato mixture with a fork.
To prepare dough, combine turmeric, ginger, and cinnamon in a skillet over medium-high heat. Cook 30 seconds or until fragrant, stirring constantly. Transfer to a plate; cool.
Lightly spoon flour into dry measuring cups; level with a knife. Place flour, toasted spices, 1/2 teaspoon salt, and baking soda in a food processor; pulse to combine. Combine 1/4 cup hot water, lemon juice, and 1 tablespoon peanut oil in a bowl. Add the hot water mixture through food chute with food processor on, and process until dough forms a ball. Place dough in a bowl coated with cooking spray, turning to coat top. Cover and let rest 15 minutes.
Divide dough into 12 equal portions. Working with 1 portion at a time (cover remaining dough to prevent drying), roll on a lightly floured surface to a 4-inch circle. Place 2 tablespoons filling in the center of each dough circle. Moisten edges of dough with water; fold dough over filling to make a half moon. Crimp edges with a fork to seal. Repeat with remaining 11 dough portions and filling to form 12 samosas.
Heat 2 teaspoons peanut oil in a large skillet over medium-high heat. Add 6 samosas to pan; cook 3 minutes or until golden brown. Turn and cook 3 minutes or until golden brown. Transfer to a paper towel–lined plate. Repeat procedure with remaining 2 teaspoons peanut oil and remaining 6 samosas. Serve with warm Marmalade.