For the Paste:
10 to 15 dried spur chiles (15g) (see note)
2 plum tomatoes (about 100g)
1 disc (15g) tua nao (optional, see note)
1 stalk lemongrass, bottom 4 to 5 inches only, outer leaves discarded, tender core thinly sliced into rounds (about 10g sliced lemongrass)
10 small garlic cloves (30g)
5 small shallots (80g)
2 teaspoons (20g) Thai shrimp paste
For the Seasoning Sauce:
1/2 cup (120ml) water
2 tablespoons (30ml) fish sauce
1 tablespoon (15g) Thai fermented soybean paste
2 teaspoons (10ml) Thai thin soy sauce or light soy sauce
For the Pork:
1/4 cup (60ml) vegetable oil
1 pound (450g) ground pork
8 ounces (1 1/2 cups; 225g) cherry tomatoes
Assorted raw vegetables such as cucumbers, green cabbage, lettuce, Thai eggplant, long beans, and more, cut for dipping
Assorted steamed or blanched vegetables such as winter squash, okra, and more, cut for dipping (optional)
Hard-boiled eggs, halved (optional)
Unflavored pork rinds (optional)
Cooked jasmine or sticky rice
For the Paste: Place spur chiles in a dry wok or carbon steel or cast iron skillet, and toast over medium-low heat, turning occasionally, until chiles are fragrant and turn a deeper shade of dark red, 4 to 5 minutes. Remove from heat and transfer chiles to a plate to cool slightly; wipe out wok or skillet and return to stovetop. Once cool enough to handle, remove stems from chiles and transfer to a granite mortar and pestle; set plate and mortar and pestle aside.
Meanwhile, place plum tomatoes in now-empty wok or skillet, and cook over medium-high heat, turning occasionally, until charred all over, about 5 minutes. Transfer tomatoes to now-empty plate and set aside to cool.
If using tua nao, use tongs to grab disc and hold about 2 inches above low flame on a gas burner. Flip disc every 5 seconds until tua nao is toasted to a hazelnut brown color, with little leopard spots all over on both sides, 2 to 3 minutes. Transfer tua nao to plate with tomatoes to cool; set aside.
Pound chiles in mortar and pestle to a coarse powder, 3 to 5 minutes. Add lemongrass and pound fine, 3 to 5 minutes. Add garlic and shallots and pound to a coarse paste with a few large pieces remaining, 3 to 5 minutes. Add shrimp paste and tua nao (if using) and pound until well-incorporated. Add charred plum tomatoes and gently pound until broken down and incorporated into paste, about 2 minutes. Transfer paste to a small bowl and set aside.
For the Seasoning Sauce: In a small bowl, stir together water, fish sauce, soybean paste, soy sauce, and sugar until well-combined and sugar is dissolved. Set aside.
For the Pork: In a wok or 3-quart saucier, heat oil over medium-high heat until shimmering. Add the chile-tomato paste and cook, stirring frequently, until paste is aromatic and turns dark red, about 3 minutes. Add the pork, stir to combine, and cook, using a wok spatula or wooden spoon to break meat up and scrape up any bits that stick to the bottom of the pan, until cooked through, about 4 minutes.
Add cherry tomatoes, stir to combine, and continue to cook until tomatoes begin to burst, 3 to 5 minutes. You can coax the tomatoes into bursting by pressing down on them with a wok spatula or wooden spoon, and you can decide whether to lightly crush all of them or leave some whole for juicy pops of tomato flavor in the finished dip. Stir in seasoning sauce and bring to a boil over high heat. Cook, stirring frequently, until liquid is reduced to a saucy consistency and oil begins to separate from emulsion, about 8 minutes. Remove from heat and allow to cool to room temperature, at which point nam prik ong can be served or refrigerated in an airtight container for up to 1 week, or frozen for up to 1 month.
For Serving: Transfer nam prik ong to a serving bowl and serve with assorted raw and steamed vegetables, hard-boiled eggs (if using), pork rinds (if using), and rice.