Bring a medium sauce pot of water to a boil. Add the rice noodles and cook until just tender, 8 to 10 minutes. Drain and rinse with cold water, then return to the pot and toss with 1 to 2 teaspoons oil to prevent sticking.
While the water heats and the noodles cook, prepare the ingredients for the laksa.

• Trim the stem ends from the green beans; cut the beans into 1-inch lengths.
• Cut the tofu into 1-inch cubes.
• Coarsely chop the cilantro; divide into two equal portions, one for the sauce and one for garnish.

In a wok or large frying pan over medium heat, warm 1 to 2 teaspoons oil until hot but not smoking. Stir in the lemongrass paste and cook until fragrant, 1 to 2 minutes. Add the green beans and as many Chinese chiles as you like, season with salt and pepper, and cook, stirring occasionally, until the beans are starting to soften, 2 to 3 minutes.
Add the tofu, coconut milk, brown sugar, and 1 cup [2 cups] water and bring to a boil. Reduce to a simmer and cook, stirring occasionally, until the beans are just tender and the tofu is heated through, 3 to 5 minutes. Remove from the heat, discard the chiles, and stir in half the cilantro. Season to taste with salt and pepper.
While the tofu laksa cooks, prepare the remaining garnishes.

• Cut the lime into wedges.
• Strip the mint leaves from the stems; coarsely chop the leaves.

Transfer the noodles to individual bowls and top with the tofu laksa and any lemongrass-coconut sauce in the pan. Garnish with the carrots, mint, and remaining cilantro and serve with the lime wedges.